For a one-story ride, elevators typically are MUCH slower than just climbing the stairs. The majority of people are quite capable of climbing stairs occasionally except, maybe, for the last 5 or 10 years.
I did see an elevator in the home of a man who was wheelchair-bound. I did not see the mechanism, but it was basically a retrofit - a railed platform (glass sides up to about 3 feet high, like you see on some wheelchair stairway bypasses) that went up and down in a square center of a stairwell, with a middle stop on the other side for the door at ground level; I assume it was a scissor-jack sort of mechanism with about a 9-foot raise; (I assume it also went down to the basement?) or maybe it rode a beam along one side. (I didn’t have a chance to check) With the open design it was practical, but an accident waiting to happen if you were stupid enough to lean over inside and crush your head. I can’t imagine it being too easy to pass the safety laws, but it was there.
Instead of an elevator, think or a moment about a door or a toilet. They’ll sell two classes of these, one lightweight version intended to be used about twenty times a day (for a private residence) and one sturdy version intended to be used several hundred times a day (for public use). The latter sort would be more expensive than the former, by a factor of several hundred.
Now, think about the kind of mishaps you’ve seen in a public elevator: Doors opening on an empty shaft, doors opening between floors, getting stuck when you badly have to go to the bathroom. This is on the good, expensive kind of elevator that gets regular maintenance. You’d be subject to worse, more frequent problems with the cheaper, $20 K elevator. And even if you’re crazy rich, you’d probably balk at having a home elevator that costs as much as the rest of your home combined, when you’re unlikely to use it more than about three times in a day. And there’s really no in-between choice.
In Korea, when people want to load lots of big furniture into a higher-floor garden apartment, they hire a truck with a freight cherry-picker feature to deliver it through a window. They hire this service twice: once when they move in, and once when they move out. (Maybe this is available in America too, I just haven’t observed it.)
Most high priced stand alone homes I’ve seen, in the U.S. anyway, have an ensuite bedroom on the ground floor that is large enough to serve as an alternative master bedroom. The norm seems to be to use this bedroom for guests, with the plan that the homeowners will move down there when they reach the age where climbing stairs becomes a burden.
Elevators are basically standard in upscale townhouses in London where the master bedroom is typically on what we would consider the third floor with kids/guest rooms on the higher floors. The elevator (or lift, if you prefer) typically does not reach the uppermost floor, my guess is that this is due to the need for mechanicals to be located at the top of the shaft. If so, this would obviously make elevators less desirable in a typical high end U.S. suburban home with only two stories.
I use to work on elevators. I don’t think I would want one in my home unless I knew how to turn a wrench safely. If you estate is large enough to have a qualified service staff then it would be OK but other wise some day there is going to be a problem.