Also say why the fuss on cars? we should all drive little box cars. Sometimes we buy for comfort.
My thought has always been, why is there a line at that cheap gas station when for only a buck more per tank I can go and fill up without a crowd at the gas station that is 3 cents higher?

It's just not about SEER it's also about quality and how the system is made.
Most 15 SEER systems are made with better parts.
Every brand has it's lower end models and majority of those models happen to be 13 SEER. There is also a RNC level too which should only be sold for new construction but some contractors sell those noise makers as their preferred line.

I bet you have a big screen tv and computers and of course lights? I know I have all that stuff and I know all that stuff cost me more than the operation of my A/C,

Remember the devils advocate,
If quality doesn't matter get the RNC unit and put it right by your bedroom window, you may not sleep much but you will save a buck.

I upgraded from a bottom of the barrel builders grade 13 seer system to a 15.5 seer quality system. The new one has hardly any blower noise in the vents and the old one was so noisy you had to turn up the tv when it was on. The new one has a lot better heating efficiency also. I was also able to get interest free financing which was another motivating factor.

I am very happy with my system.

It cost more to make a higher SEER unit, more material at the least. Higher cost = higher markup. They feel compelled to mark it up extra generously too, take some of your payback savings. They get theirs now, you get yours over many years.
Caveat emptor.

himo

your reasoning on the surface is valid. however, look behind the cost and see what you get. many of these 13 SEER units are just a POJ. does the condenser have full coil protection? what is the db rating? does it have a sound blanket? does it have the safety devices a homeowner would want to protect the condenser when operating out of the norm? there are other features as well.

It is interesting that you see many consumers go top of line in heating and btm end on condensers.

IMO

And does it get the $1500 tax credit?

If you figure the tax credit and some utilities have pretty big rebates along with having actual demand defrost along with higher efficiency overall. Quieter and more efficient and a good warranty. There are many things that weigh into the decision.

I'm not in the industry, but as a technically aware shopper trying to learn enough to wisely go about replacing my elderly system, I haven't seen that kind of difference if you compare in-family hardware. You can get 16 SEER (at which point the IRS will probably hand you a check for $1500, btw) without the bells and whistles that add another $2K to the system.

Those features are fun and feel good, as the others have said, but that's a totally different reason to spend money.
Talk to a couple more dealers and ask your question about payback. If you find one who'll explain your choices and help you understand them rather than push a top of the line system at you (capitalism at work, which I actually admire) you may have the beginnings of a business deal.

I bought a 13 SEER thirteen years ago. I should think a 16 would be called for now. I'm not gonna explain why, you either get it or you don't.

Our builder-grade, SEER-what?-8? (circa 1993) unit worked just fine for 15 years. Replaced it with SEER-16. Nice unit. Much quieter, smoother running unit. But when I talked replacement with our HVAC outfit, they didn't push the high-end units. And I didn't have the impression that the SEER-13 units were junk.