That's not exactly true. For one, all the local affiliates have their own budgets, their own expenses, revenues and staff. Up until this year, NPR was specifically prohibited from collecting donations from listeners. If you had gone to npr.org and clicked "donate" it would force you to donate to your local affiliate. Affiliates do not give NPR a cut of their donations. Instead they pay (on a sliding scale I think) for the rights to content produced by NPR. If you look at the sources of revenue for any given affiliate, it will probably be mostly donation from listeners. So taken as a whole, public radio is very much paid for by listeners.