Regarding the broader issue, teachers seem to expect to have their pay be competitive with industry based on degree level rather than on skill. I mean, seriously, how much is someone with a masters degree in education worth outside of schools? So they just say "masters degree" so they are compared to engineers and nurses and people like that.
Putting that aside, assuming all masters degrees are the same, let's look at teacher compensation as a whole and compare it to industry. Hmmm, can't find my company's policy on tenure anywhere. Oh yeah, nobody anywhere in the real world has a guarantee that they can never be fired! Wow, I might take a little less if I had that. Maybe if the teachers gave that up, they could get a higher salary? Oh, that's not on the table, ever. Well then accept that with a guaranteed job for life tenured teachers cannot compare their compensation to anyone in the real world and move on.