Well that's a topic that intrigued me recently.

Here in France there was already some debates about how worth it was, mostly because it takes a few years to compensate the cost of production of the battery. But in France we think of the electricity as basically carbon-free (our energetic mix is something like 70% nuclear, 7% gas+coal, then "clean" energy)

However, in the world I think something like 70% of electricity production is fossil (with ~40% of coal), I don't get how electric cars are even a thing, say in the US?

It’s not remotely easier. Trains carriages are easy to build, but the infrastructure is not. You have to move and extend roads, demolish buildings, lay the rails, build bridges, if you go underground there will be lots of digging and engineering work to protect nearby buildings, and don’t forget about maintenance. It is only profitable when the population is high enough and people have the need to travel to set places en mass. Otherwise it is just fantasy. If you live your whole live around any city Center, I can understand that you are not going to drive . But plenty of people lived in a tiny town of population under 10000people .

Trains are electric. They use diesel generators to power the wheels.

In cities, yeah. Outside cities, impossible

But I'd love to rent autonomous electric cars to move

You ever try taking your new mattress and bed frame on a train?

This isn't a binary. We need both robust public transportation and electric cars (with an electric grid supplied by renewable energy). Public transportation can't take you anywhere at anytime -- it's all a game of statistics and demand. If 12000 people want to go downtown at 7 pm, and 3 people want to go the opposite direction to get to work to start their night shift, you're going to see buses and trains headed downtown but not the opposite side of town.

Public transportation is best served for commutes and travelling to popular areas, and that's where the majority of emissions are coming from. Cars can supplement with everything else

Why is it that trains are always proposed as the alternative to cars? I, for one, really want PRT to succeed. It seems to be the best middle ground between efficiency and convinience.