> Sadly, I think this is only easy to accomplish in mid-sized densely-populated cities (<= 250000 inhabitants), unless there's a lot of planning and investments done.
You are right about the "easy" part, but it can definitely be done. In fact that's what Tokyo feels like, and it's the largest city/metro area in the world, with 38 million residents.
I moved here 2.5 months ago and I'm so glad I did. It's a huge metropolis where one can comfortably live without owning a car. On top of that, it has one of the lowest crime rates among the world's big cities:
You are right about the "easy" part, but it can definitely be done. In fact that's what Tokyo feels like, and it's the largest city/metro area in the world, with 38 million residents.