Re: It all has to get paid for somehow
"Does PBS (in the US) need to routinely run ads? (I don't know/can't remember)."
Not as such. From time to time they'll have fund drives where people interrupt the shows to beg for money from the viewers. I'm not sure which is worse. I suppose on a small scale, shows on PBS (and NPR) are often sponsored by one or more backers. "$SHOWNAME is sponsored by JimmyWidget, makers of fine widgets for discerning tastes and The Croydon Arts Council, presenting Oliver Twist from March 3rd until April 1st at the Dabs Theatre".