FWIW, most people who use wheelchairs have a little mobility. Some can stand and walk a little, so they might be able to use some full-sized appliances, or at least get up and step into a bath. Some people can use an appliance to pull themselves into a standing position and hold it briefly, so they can use the upper shelves, and not let the space go to waste. Most people can get into a bath tub, either by transferring using upper body strength, and possibly a board, or by using a combination of upper body strength and limited mobility.
I’m just saying that disabled people have lots of choices and ways of doing things.
At any rate, the possibility of getting stuck in an elevator is probably frightening to anyone who depends on medication or needs things attended to, and maybe can’t crawl out through the trap door on top like you always see in movies. You can put a phone in an elevator, but this presumes landlines, because cell phones usually don’t work in elevators.
Probably people building big enough houses have thought about them, and rejected them as more trouble than they are worth.
And, my aunt and uncle looked into stair-mounted lifts. Insurance sometimes helps pay for them, and they are something middle class people can manage. People who can build million dollar homes can probably put in chair lifts even if it’s just for someone who visits once in a while.