State governments across the country are laying off teachers, closing public libraries and parks, and reducing health care services, but there is one place they could get $23 billion if they could only agree how to do it: Internet retailers such as Amazon.com.

That’s enough to pay for the salaries of more than 46,000 teachers, according to the U.S. Bureau of Labor Statistics. In California, the amount of uncollected taxes from Amazon sales alone is roughly the same amount cut from child welfare services in the current state budget.

But collecting those taxes from major online retailers is difficult.