Want to make this a very open discussion on a topic I have no opinion on and have limited information on so really want to hear other peoples experiences and thoughts

Basically some friends in Tokyo noted that for some reason their friends/extended family in Tokyo tend to have less kids and have them later than their friends/extended family outside Tokyo.

While I can understand that the busy Tokyo life can mean careers take a priority over kids but at the same time kids cost money but salaries tend to be lower outside of tokyo (though cost of living is also lower which offsets that somewhat).

So in everyone elses opinion is my limited view similar to most other peoples? And if so how are parents outside of Tokyo pulling it off on lower salaries? And if not is it actually easier to raise kids in Tokyo?