On the same track,
We(my union and associated ATCA) didn't accept the difference between ATCOs with university degree bachelor,MBA or DBA level,as well ,either connected or not with aviation and secondary school ATCOs.
As long as they working the same job- the same salary.
Things change at management level but there is also( not in my company) in surrounding ANSPs cases that qualified ATCO with secondary education earns more money than someone with university degree. Why?
Because, union said: If you work as an ATCO 12 or 15 years,than you may choose: ATCO salary with 15(12) years of experience or salary as someone with university degree. In most cases people opt for the first case. salary is better,definitely. Also if you move to some lower position you may retain your ATCO salary.
I also have in mind that here in Europe people are more concerned and prefer social type of state. USA is more profit-without love.