Like everyone above says, the cabs should be tight to the range. Our kitchen cabs are within 1/8" of the range on each side and the granite is flush. However, it is possible that your cabinet maker really does mean 1.5 inches ... because that did happen to us recently with a new build townhome we bought. Never occurred to me in a million years that this was even possible, but here that's what the builder actually gave us and then tried to pass off as 'standard' in our PDI. Needless to say I threw a complete and total hissy fit lol, and they did come back and add filler panels in the days after we closed. I'll show you pics of it with the gap so you can see just how completely ridiculous it looks. Here's our home kitchen and what the flush cabs should look like: And here's our townhouse kitchen when at closing. Whatever you do, ensure your cabinet maker does not copy this look. :-)

GC's grandson is doing GREAT. He gets to go back to school next week. And we'd already decided to delay the range. One of the reasons I chose this GC is he has a reputation for taking mid-range (for our area) renos as seriously as high-end. If we'd chosen different finishes we'd have kept to our initial 25K budget. When we went with the Caeserstone and higher-end appliances...well it's going to be closer to 35K. Which isn't COMPLETELY out of bounds. (The Husband set a 25K budget so we'd stay under 35K.) Our GC was the only GC of the five we interviewed who said "Of COURSE you can do a kitchen for 25K. It will all depend on finishes and appliances." Everyone else said some version of "25K is too small a budget." (We had a 5K "uh oh" fund set aside for unforeseen problems prompted by remodeling in an older home...that turned out to be unnecessary.) Well--25K WAS too small a budget--but only because DH fell in love with a class C Caeserstone, (I was actually pusihing for laminate--appropriate to the 1966 house, and very functional) and $35/sq Jasba Lavita tile, and the racks and looks of Electrolux Ikon gas range. ;^) And when we realized that a Miele DW was only $200 more than the kitchenaid...well... a couple of hundred here, a couple of hundred there... (I found all the deals...got our oak floors, INSTALLED, for $1600. And found great pendants for over the bar on Etsy--three for $350. And they will be stunners!) Maybe I'll straighten up and take pictures today...so y'all can see the general effect...mid-stalled-reno.

If you have a slide-in range, the gap is normal but there should be a cover piece of metal or counter material back there. If you have a stand-alone range, I would suspect the gas line or cabinets that are out of alignment. The gas line question is easy - take the bottom drawer out of the range and look.

If the gap is a .50 inch or less: have this same issue. i am going to use this self sticking pvc stainless steel color finished trim to mitigate the gap. here is the Home Depot link, but I also found the exact same product on Amazon for the same price. pack of 3 - 24” pieces for $19.99: https://www.homedepot.com/p/Aspect-Stainless-24-in-Vinyl-Backsplash-Trim-3-Pack-935-50/313854875#overlay