In particular, though, I wonder why no one in the West (as far as I know) has taken up the idea of "unten daiko"?
Imagine that you've driven to work and get asked out for a drink afterwards. You can't go, or at least you can't drink alcohol, because you've got to drive home afterwards. Annoying! Or, imagine you've been invited to a party, in a place that's not well served by public transport. Obviously, if you mean to drink you can't take your car, and will have to get a taxi both ways. Expensive!
This is where unten daiko (運転代行 - roughly, "substitute driver") comes in. The unten daiko taxi has two drivers. One gets into your car with you and drives you home, while the other follows behind. At the end, your driver hops back into the unten daiko car and they disappear into the night. Yes, it's a bit more expensive than an ordinary taxi (you're paying for two people, after all, and presumably they need extra insurance for driving other people's cars), but now your car isn't stranded far away from your house.
This system seems such an obviously good idea for any place that doesn't have excellent public transport (i.e. almost anywhere outside a big city) that I can't believe it's not found its way to the West. So, if you feel like it, set up an unten daiko company with my blessing, and watch the profits roll in!
(I only want 5%.)