[TheSpiceIsLife]

I live in Australia, here stair climbing wheelchairs are obviated by wheelchair ramps in to every public use building and commercial building. Wheelchair bound people are also given subsidies to have ramps installed at their homes too.

Additionally, I'd hazard a guess that price effects consumer uptake. If the the stair climbing feature costs, probably at least(?), $5,000 to $10,000 dollars extra fewer people are likely interest.

edit: a word and a space