the US already spends a tremendous amount of money on education. the overall spending per-student is comparable to that of western european countries, and poorer US cities tend to spend even more, interestingly enough. maybe people don't want to spend 1% more because they just don't believe they'll get much for it.

as for teacher salary, someone with a bachelor's and no other certifications would start at around $50k in my (poor, east coast) city, which is roughly the median household income. this is not much less than tech startups will offer new CS grads in the area. city public school teachers can make over $100k by the end of their careers. certainly not enough to live like a king, but that puts them at about the 80th percentile for household income here. imo, that's pretty good for a public employee.