If you're spending more than a half hour at a coffee shop, you're there to work. You're playing this game where you're trying to figure out whether you've bought enough coffee not to look like a complete mooch. You're also hoping the free Wi-Fi is up and working, and that nothing is going to happen that will disrupt the work you're doing.
Workshop offered a great cafe menu, but most importantly offered assurances around seating, quiet spaces, and high-quality Wi-Fi. It was a hybrid model, and one I don't think there are decent laws established for them. This is a bummer, and probably a bad application of by-the-book zoning in a city where those same laws are being used to prevent way more important things like improved housing density.
But that's SF for you, I guess.