The states can indeed do this, but when they can funnel Federal funds in for their highways, schools, and all the other things they used to be responsible for, instead of having to use their own money, what's not to like?

Up until around 1965, there was essentially no Federal education funding at all, and oddly enough, people educated under that system built much of the high tech society we live in now and put men on the Moon. Until 1979, there was no federal Department of Education, either. Since then, well over half a trillion dollars has been pumped through that department alone. Has it helped that much?

Public education cost per student, in constant dollars, has tripled since 1963. In that time, teacher salaries (again in constant dollars) have gone up by only a factor of 1.3, and the number of students per each teacher has dropped in half since the 1950s. Have our test results been increasing accordingly? How about other education results?

Average cost per student in public schools (including all funding sources, local, state and Federal) is now floating between $9,000 and $10,000. Average tuition paid in private schools is around $7,000, with parochial schools generally being lower (in the $4,000 range) and secular private schools higher (up to $13,000) than this number. The average tends lower because there's more students in the parochial schools.

Results are never considered as important as intentions with government programs, and when you hear how essential to human existence a government program is, the original source is usually someone inside that program.