Furthermore, your PBS example doesn't count: PBS is not a company, they're a non-profit that survives off donations and government funding. If you like their app, you should really consider making a donation.
PBS is a corporation. Just because a corporation is non-profit does not mean it doesn't count. See also: Wikipedia.
Regarding donations: I didn't say content should be free. My second example was Netflix after all. I said that having ad-free on-line children's programming is possible technically and economically.