Because they can! Seriously, it's a limited high-end market and they don't mass-produce them. Even standalone counter-depth refrigerators are overpriced in my opinion. You're basically paying a lot more for a smaller fridge - but they appeal aesthetically to a small portion of the populace who are willing to pay for them.

What Brands are You looking at?
I bought a Jenn-Air on June 20, 2006 and paid $4588.
We love it and it has been trouble free.
You can save some money if you look at last year's models
and some sites are offering a "Free" 10 year warranty with them.
For a built in you do need a W I D E one, when we designed the kitchen, I told wife, we are designing around a 48 inch Fridge and we did. No Regrets!!!
My Model is JS48CSGXDA (it has since been replaced by the same number except the last letter is "B".
If you check Consumer Reports, You will usually see the Jenn-Air Fridges ranked #1 in reliability.

Gary

I'm looking at KitchenAid - which is very similar to the Jenn-Air and relatively well-priced compared to other brands. Still much more expensive than a freestanding though. I'll see if I can find last year's model somewhere. Thanks!

Most built in fridges don't have two compressors. Their price is based on perceived value only. Even though I know I'm getting ripped off, I would buy a built in because it looks so much better to me.

Well, also, the design of the built-in one has to account for limited airflow. It has to be more space efficient with the works to make the storage area bigger, etc. Why does a laptop computer typically cost more than a similarly powered desktop one (with monitor and entry devices)? Same thing.

In addition, because it's for a high end market--or they think it is--they usually put more and fancier features in them.

It's true that they're priced at what the market will bear, but there's also more in it.

Many of the simple, lower cost fridges, especially the side by sides, are made for the apartment market. They work perfectly well in houses and get used there too, but the economies of scale that allow them to manufacture a lot more units and sell them at a much lower price are driven by apartments.

"Their price is based on perceived value only"

Oh, come on. You don't think for a minute that the ACTUAL components that go into a Sub Zero or Miele buitin fridge are the same quality as those that go into a garden variety Kenmore or Whirlpool fridge do you? Better quality compressor (so those guys don't lose their #$#&* under their 10-12 year warranties), higher quality stainless steel, better hinges and drawer runners, more and better lights, ect.....This stuff all cost $$$ and everyone up and down the supply chain gets their cut on the more expensive parts.

Does this make up the entire difference? NO, but the high line product's raw materials cost more than the comodity product.

Great question in the title. Great thread so far.

When you encapsulate a computer, heat accumulates (temperature rises) since air flow cannot convect and take heat elsewhere. Same for a fridge, but worse by several orders of magnitude because Humidity in your room's air prevents the fridge from using evaporation efficiently as a cooling mechanism in combination with moving air, convecting or fanned. When the fridge is surrounded by a five-sided box, i.e. built in.

I agree with the above posts, all of them. Plllog was the first to point out the heat capsule effect. Clinresga was the first to point out that substantive differences exist. The big one is that you are creating a moist hot greenhouse (dark, not lit up) if you enclose a fridge, since it spills humidity out from its guts as per design. Humidity enters the fridge when you open and close its door and high RH room air enters, gets cooled and drops its humidity inside the cooled compartment -- and this has to be spilled back out into the room air.

Managing moisture is the dilemma. How to get rid of h2O, in a five-sided box.

Heating and cooling are easy to do. You still need to plan for the excess heat to escape somewhere, and that ALSO costs more money when the fridge is built-in or fully integrated.

Cost of raw materials is a minor concern, as in many situations where systems are complex.

I have a long post in another thread that answers some of the technical questions about how heat is exchanged. Linked to below.

These are my findings, and I am not a refrigeration engineer. I am signed in to a refrigeration engineers forum and have participated in discussions there.

I agree with the basic question, as to trying to know what a built in does that how, so that we as buyers can pick and choose and Also Help Design the Devices we want next to have.

HTH
-david
p.s. a few other threads:
"Volume of air needed to operate a small manual refrigerator"
at http://ths.gardenweb.com/forums/load/appl/msg031555471649.html
"Cheating the system: fridges" : "...if you box in a fridge, you may be asking for trouble..."
at http://ths.gardenweb.com/forums/load/appl/msg0822321916417.html
Can I Panel a Samsung Refrigerator?" : "...frost on gaskets..."
at http://ths.gardenweb.com/forums/load/appl/msg1212390218791.html

Here is a link that might be useful: technical answer, why fridges re-generate humidity

So far this is the only site commenting on the difference between your "kitchen" refrigerator and a "built in" professional refrigerator. The things that stand out between the two is
1 construction
2 Quality
3 size (professional being smaller)
4 depth (professional being counter depth)
5 cost
Construction and quality is pretty much the same with the exception of materials, professional being a heavier gauge

Size, I presume is due to the restriction of being counter depth so they have to be wider.

Cost, I cannot find a justification for the 3-9 Thousand dollar cost of a professional.

Warranty does not mean much as it is really rare to hear of a "kitchen" refrigerator lasting less than ten year unless it is used in an apartment. But who would ever put a professional refrigerator in your standard middle class apartment?

Humidity control, they both suffer the rigors of frequent opening and closing.

Cost of operation, I have no clue as I can not find any info on this. Logic would dictate that there has to be some reason for the differences between the two but darned if I can find the reason for the differences other than design of construction. Why a restaurant would want a professional would be the accessibility to products store in a timely manner (time is money in business). Puzzling is all I can say.

I think it boils down to the previous observation that one buys a Professional built in for home use is fashion.

@ antss - I'm not sure what you are basing your comment on. I have an $8000+ built-in Thermador (which I will never purchase again). It's four years old and I am replacing the Samsung ice maker it comes with for the second time in two years. The warranty certainly isn't 10-12 years for anything and the Samsung ice maker is a piece of garbage...why they didn't use a Bosch ice maker is beyond me.