How many frail people unable to walk a block are there? Taxis absolutely suffice for your situation, if there is heavy rain or snow fall. In all other weather, they will be able to wheel themselves back home - if they're unable to operate a wheelchair they probably don't need much transport anywhere either.
How are kids going to sport practice? Ever heard of bicycles? Heavy equipment is usually short at the sport facility, everything else fits in a bag. Sure, heavy rain absolutely sucks on a bicycle but wearing a jacket and rain resistant pants is enough for usual amounts of rain. Snow isn't that bad either, as long as the roads are properly salted. And even then, you can drive on icy roads with your bicycle as long as you're careful.
Source: I frequently drove 5km to school and 6km to sports practice as a child. The worst thing was the difference in altitude, not the weather (there were two 12% inclines on either way).