I will never understand why, for example, restaurants and movie theaters (most of them) tolerate behavior this is, to say the least, boorish and disruptive to the experience of the other customers
As someone that's done it, I guarantee that evicting someone from a movie theater will be far more distracting than their cell phone. If they're obnoxious enough that theater management is involved, then they're probably also not going to politely get up and leave when someone asks them to. At that point, the management has two choices: let them remain or call the police. This won't be considered a particularly high priority, so you can expect a half-hour wait for the police. One they get there, they''ll want the house lights brought up (at a minimum; they may ask that the movie be stopped as well) before they escort the person off the premises.
That said, I have seen a "patron" carried out of a movie theater after being pepper-sprayed. It's a bad idea to lay your hands on a police officer when they ask you to leave...