If I recall correctly, the amount came from a national study of the technical debt, if you will. For example, my city is a fairly large city, more than a million people, and it's using pipes that are over 100 years old, so that's probably not good, right?
Its a typical situation.
I do agree, we should tax the rich. Even if we magically had the funding yesterday, there are an astonishing number of complexities involved in fixing the aging infrastructure, not the least of which is the zero downtime tolerance.