Seems more like they're trying to get abandoned accounts down to $0 in their wallets so they can cancel all the abandoned accounts wasting space on their server than actually trying to charge people a fee for something.
People literally just give up on their PP accounts, because it's not worth your sanity (dealing with Paypal's "customer service") for something like $100 left in the account.
Not to mention that almost every bank has fees too. Overdraft fees are charging you because you didn’t have money!