The problem is that there are so many grads who refujse to work anywhere outside of their metropolitan area.
I am somewhat guilty of this... not taking the highest true private practice offer I got because I want to move bavck to where I'm from. I'm fortunate that where I'm from isn't as saturated as metro NY, LA, SF, Houston, DMV, DFW areas... but I'm sure as Hell not gonna make what I would in the upper Midwest. There's nothing wrong with the upper Midwest... if I didn't have any friends or family I would definitely entertain moving. The best money is in the places with the smallest selection of restaurants and fewest flight destinations, and that's not a secret.
I used to have no sympathy for people who accepted lower paying jobs to live in a certain geographic area until my priorities changed and I became one. You don't have a lot of people chasing the geographic arbitrage friendly jobs not because those places suck to live, but it's not where the new grads grew up. People in their early 30s have aging parents, nieces and nephews, kids of their own they may need grandparent support for, dental school friends from their in state schools who are out in practice and can refer to them etc