Across the western world, elderly benefits increasingly outstrip the growth young workers paying taxes for their benefits are able to eke out. I do not think they need free taxis as well.

For UK in particular look up triple lock pension.

London also has the highest number of non-citizens staying in four star hotels on the tax payers dime.

I think the elderly former tax payers can have all the taxi vouchers they can reasonably use.

They just need to mutter “asylum seeker” occasionally.

There's not many taxis in most places, I come from a town of 400 people it'd be a very uneconomical solution.

I'm not saying it's great for them to drive, I just doubt there's a way to fix it in these sort of places. My grandma cycles to the small store for most of her groceries everyday, it's only the big store she drives to bi-weekly. Honestly the cycling is probably more dangerous, and there's some elderly in my town who're pushing 100 cycling daily.

Public services don't need to be 'economical'