Looong ago teacher's pay used to be really dismal -- many had to take summer jobs to help finance the rest of the year when they were teaching. Then they got unionized, and wages became comparable with other professions requiring 4 years of college, e.g. an engineer or whatever. Next the different school districts started changing their individual education requirements, which made it rough since a teacher looking for a job was often under-educated, so they didn't qualify, or over-educated, so the school district wouldn't hire them feeling they'd leave for more money at 1st opportunity.
Then the unions started getting carried away, demanding more money & benefits, mostly getting the benefits -- an individual teacher's retirement benefit in some places costs the state over $1 mill. That meant school principles & school district employees made more, unionized or not, just to keep up. Administration was always political, but things Really got political then, as these jobs along with teaching became highly desirable just for the income & benefits, whether you liked teaching or not, had Any skills at it or not.
So today it's almost impossible to fire or reduce the pay of many teachers &/or school board employees -- in New York they have many teachers they won't let teach, so they report daily to rooms where however many teachers just pass the day however they like.
Charter schools are something fairly new, not every city or state allows them, but they're basically private schools that'll take anybody, competing with the public ones run by the gov. -- the controversial part is the money to run charter schools comes from the pool of funds the gov uses to pay for the public schools. And charter schools often have things like the merit-based pay your wife gets, WR. The unions thoroughly loath the concept -- in the unionized public schools everything is based on seniority, so the more years you have in, the higher your pay, & the safer you are from any layoffs should they close a school. If a teacher or teachers don't do their job & student test scores fall, typically they'll lower the curve until they can re-write the curriculum making it easier.
Interestingly Microsoft got involved some years ago helping the federal gov come up with methods to track performance so they could identify problems & apply resources to fix them. You don't hear MS mention that now as the whole effort became a political hot potato -- read yesterday that according to fed. gov. reporting, unions spent I think it was $4.5 bill from 2005 -- 2011 on political activism & donations, so it's small wonder.