I think most people in those mayors drop out, not overall. My guess is that people know you can make a lot of money there but then realize they don’t actually like it.
I don’t think it’s a big issue though, some public money might be “wasted”, but you give everyone a chance which find perfectly acce.
It’s been a while since I played 5e, but if I remember correctly you could do some fuckery with Haste and/or Sorcery Points if you don’t follow that rule.