Make cities decent places to live, grow a family, and hang out instead of just workday commute destinations.

More people should be living in cities. We need not only fewer cars but also fewer freestanding, single-family homes. Continental Europeans trounce Americans in land management in part because continental Europeans do not abhor density the way Americans do.

Don't worry, your opinion will change about 12 seconds after your first child arrives.

1) I'll probably never have children.

2) Childbearing couples seem to function just fine in relatively dense European urban housing. The idea that we somehow need space to spread out is largely confined to the Anglosphere, which is why land management problems are so much worse in the Anglosphere.

If you've ever been to Tokyo, Taipei, or any old European capital, you'd know that "crowding people into cities" can be a good and beautiful thing, when the infrastructure is there.