"You're wrong" combined with hard evidence is apparently not enough to convince people. Human nature does not respond kindly to threats. And being mistaken is perceived as a threat. The fear of acknowledging one may have been in error is perhaps an unintended outgrowth of our formal schooling where mistakes are unfortunately equated to one's worth and even identity. Nyhan and Reifler have studied how and why a large number of Americans believe in misinformation. Here is an abstract of their paper:
So, learning from the above, here it goes. First, although some of us may not have realized yet how important teachers' salaries are to the quality of education, this does not make us lesser human beings. Second, since graphs are much more effective, here is one which I have modified a bit (I included the Philippines). This graph is originally from Dolton, P. and Marcenaro-Gutierrez, O. D. (2011), If you pay peanuts do you get monkeys? A cross-country analysis of teacher pay and pupil performance. Economic Policy, 26: 5–55. doi: 10.1111/j.1468-0327.2010.00257.x
I hope I have made the point this time that teachers' salaries are correlated with learning outcomes.