They're expensive, but massively more efficient than other transport. Plus they reduce congestion for anyone who doesn't have easy access.

I could understand why say, Lagos wouldn't have effective mass transit. But it's hard to see why major developed-world cities can't justify the investment.

I think people misunderstand my GP comment. I am VERY pro subway and public transport in general, and I go by bike whenever I can. But there’s a tool for every job, and one subway line won’t solve the same problem a thousand air taxis are going to solve. They don’t even play in the same league. One connects city parts loosely together and relies on other last-mile means of transport (walking, taxi, park&ride, kiss&ride, bike,...); while the other is a whole-in-one, it’s more exclusive (use once per month vs twice per day) and way faster (minutes instead of hours).

Do we need more subways? Heck yes! I want one in my hometown. Do we want air taxis at the same time? Well, why not?