I think my reason (1) explains your (b). As for (a), I agree that a lot would not be in politics but, if you have seen it first hand, academia sucks the life a

I think my reason (1) explains your (b). As for (a), I agree that a lot would not be in politics but, if you have seen it first hand, academia sucks the life and minds of out of early stage researchers in a way that other jobs do not. The salary means they are comfortable enough not to complain and no time for it anyway.