It is a very easy problem to solve, but the developers do not wish to do so, in my opinion. I know this because there have been times when BBs have allowed players to join countries with few managers. So they can do it. They could announce right now that during next off-season there will be an open enrollment for managers in countries with x+ number of users,nallowing them to join any country with y- number of users, up to some quota. Teams would have to start fresh. There is a French guy who joined Thailand a few years ago. He doesn't speak Thai but they allowed him to switch, so why not do it on a larger scale and see if it evens out the league sizes a little bit?
Once I scored a basket that still makes me laugh.