A blanket statement that "teachers ought to be paid more," is obviously nonsense. Some teachers are well-compensated and some not. The teachers in my own public school district can make 6-figure salaries when they kick into the high range of the scale after a dozen years or so. Are the worth "more"? Probably not.
The point is that collective bargaining is NEVER appropriate in the public sector, and when applied to teachers, it is an abomination. Since most cogent observers, starting with FDR, realize that this is an abomination, many taxpayers are resentful of the wages, benefits, and retirement expense that they are compelled to pay as a result of this specific abomination.
To elaborate, collective bargaining is appropriate in very few situations, and only in the private sector. It is appropriate where there is a surplus of available workers who can do the work, or where skilled workers are simply not in a position to bargain individually for fair compensation. Basically, common labor and skilled trades.
In the public sector, on the other hand, the politicians in charge of the negotiations with the CBU have a vested interest in keeping the employees happy, and they are totally insulated from the costs of the wages and benefits to which they agree in the CBA. So if they pay "too much" or have overly generous benefits, or have incredibly unrealistic retirement provisions, "Who gives a shit?" The entity will not go bankrupt; it will just raise taxes to pay the cost.
With respect specifically to teachers unions, the teachers unions provide hundreds of millions of dollars in cash and in kind to support politicians who are generous to them at contract time, thus conspiring to fuck the taxpayers year after year. Successfully, in many cases.
A competent teacher is entitled to a substantial package of wages and benefits, even though they work a job that is, to be kind, somewhat less than full time. If I were emperor I would establish a national pay scale for teachers with local cost-of-living factors, and require every school district in the country to abide by it. In today's terms, a starting teacher would be paid about the same as a GS-5 and a "Master Teacher" as a GS-11, fill in the blanks. Let the locals figure out how to pay for it.