"Public education is a socialist monopoly, a real one." - Milton Friedman
Depending on your definitions of "public", "socialist", and "monopoly", this statement is either false, or true but a tautology.
If you define "public education" to mean "government-run education" and "socialist" also as "government-run", then this is clearly true, but a tautology: Yes, all government-run schools are government-run. The government has a monopoly by definition. It's like left-handed people having a monopoly on being left-handed.
If by "public education" you mean a more general definition, then the existence and legality of private (i.e. not government-run) schools clearly illustrates that there is no government monopoly on such ventures.
There is no correlation between educational spending and educational achievement. None.
I don't know whether this statement is true or not. It certainly wouldn't surprise me if it were true, if we define "educational spending" as government spending (e.g. as raised by taxes).
What
would surprise me is if there were no correlation between
school district socio-economic status and educational achievement.
I remember when I was young, the area I lived in (suburban L.A.) had a number of different school districts, as well as a wide spread in socio-economic status. In our area, the kids in the wealthier school districts generally went to college, and the kids from the poorer school districts generally didn't.
Two possible factors that
may explain this are as follows:
1) Expectation. In the more well-off school districts (in one of which I was fortunate enough to grow up), it was simply assumed (by parents and peers) that one was going to college. Getting into college was not seen as an achievement, but simply as the normal state of affairs.
Not getting into college, on the other hand, was seen as a great failure. In the poorer school districts, it was the other way around: Going to college was seen as a great achievement, whereas
not going was the regular state of affairs. This makes sense in a circular way: The better off the parents, the greater the probability that they themselves went to college, and thus the greater the probability that they'd expect their offspring to go.
2) Private funding of public schools. In our (well-off) school district, a large part of the schools' funding came from non-government sources: Bake sales, school funding drives, private donations in the form of no-strings cash or as money for a specific project (e.g. a building or playground), etc. This private funding was invariably local, generally given by the parents of the students themselves. I would expect such private funding to be greatly reduced in poorer districts. Any study of correlations between educational spending would have to be careful to control for this, and not just take into account direct tax-generated government outlay.
The pretense that more money will "solve" the problem has been argued by teachers' unions for decades, utterly without success.
Money may or may not "solve" the problem, depending on how you define the problem. As I've said above, if the problem is lack of educational achievement, then it would not surprise me if money does not solve the problem. I don't know.
But there are other problems. I give you the following, admittedly anecdotal, true story to illustrate what I mean:
When I lived in Oakland, CA a few years ago, I knew a woman who was an elementary school teacher in an Oakland school. The school had so little money that there was
literally no money for supplies for the teachers, except for the following: Each teacher was given one number 2 pencil for each student for each year. That's it. No paper. No pens. No erasers. No paint. No
books. Everything else she needed to run a first grade class for a full year had to come out of her own meager salary.
Could her "problem" have been solved with more money? Well... yes. By definition.