I've been a public school teacher for 30 years. I've heard it all. The problem is simple. The American K-12 model is a socialist one. Think of it this way. The best teacher you ever had in your life and the worst teacher you ever had in your life made the same salary. That's right out of the USSR.
The college model in America is much more free market. A physics prof at Yale makes 5 times the salary of a PE teacher at Florida A&M. That's why foreign students want to study in America at the college level.
A merit program to reward good K-12 teachers and punish the bad ones would require the abolition of tenure and the NEA. Then, allow supply and demand to dictate salary.
We have that model now -- a history teacher in a "good neighborhood" with a high tax base makes significantly more than a teacher in a "bad neighborhood" with a low tax base. Not surprisingly, the teachers in the "good neighborhoods" tend to be better qualified.
So, all teachers do not make the same.
How about allowing the market to reward and punish good or bad teachers? It works in University as you noted.
Simply make education competitive. In lieu of property tax, charge tuition. This is obviously problematic WRT poverty kids, but we've already got some really bad problems. The poverty thing can be worked with just like lunches or similarly.
jmho