Amazon still isn't quite there - that "house kit" is offered by a third party, and I am not sure anyone rational would just drop that kind of money on a credit card for a third party on Amazon...
Now, if it said "fulfilled by Amazon" - or it went to a different section of the site ("Amazon Dwellings" - I dunno) that was clearly an Amazon branded product, manufacturing and fulfillment system for houses, that'd be a different thing.
I'm not sure how Sears did it way, way back when. But it was probably closer to something like a dealership, where you went inside a store and sat down and worked out the paperwork, etc - then paid the down payment or in full or whatever, then had to go "back home" to arrange shipment from the (likely train) dock or such out to your land...
What I could see Amazon getting into would be shipping container houses/pods/etc - or something like small houses (in conjunction with Ikea maybe?). I know Amazon has at least one offering of a container house, but again, it's third party. What I'm envisioning would be something you just go thru a designer app to come up with the interior layout for the "pods" in the standard container sizes, then tell them where you want it to be delivered, and it arrives on your property ready to be offloaded, with a large Amazon logo on the side (looking like a standard shipping container until it is "unwrapped" or "assembled" more or less. With everything included to make it stupid simple. Heck, if the land sale could be included in it, so that all bylaws and such were taken care of (water, electrical, sewage, etc), plus all the contracts and such for cement foundations or whatnot - it would be one heck of a housing solution.