People who live in a community where you can store your airplane in a garage and then commute from your garage to the runway aren't going to partially own a plane.

That's where you'd be wrong. Many are shared. Just because one of the owners lives beside the runway doesn't mean it's solely theirs. I'm not the only one to say this. https://lemmy.world/comment/3346098

What would be the point in having that kind of a property but not being able to use it because you only got to see your plane one week per month?

Save money first and foremost. It's a win-win situation for all parties involved. And one week per month is a lot of time. You don't know what the arrangement is for those involved. The time share could be wildly different depending on each pilots desires.