Cars

If someone wrote a new business plan for some kind of transport system and said Oh, it'll cost a fortune because you'll have to build factories all over the world, constantly rebuild horrendously expensive road systems, sacrifice thousands of people every year to violent death and injury, suck up totally un-renewable natural resources to build, maintain and power it, Oh and it'll also contribute to pollution more than any other single industry, the person evaluating the system would reply Are you completely crazy you crazy, crazy, crazy fool.

And you would say - you wouldn't have to sit next to anyone on the train.

And the person would say - well, that's all right then. Bring it on.

Harrumph.