We can all easily imagine circumstances in which a manager of a coffee shop or restaurant might properly call the police to ask them to remove loiterers. These are places of business. There’s nothing wrong in principle with calling the cops on non-customers who are taking up space. And there’s nothing wrong with police asking people to leave private property where they aren’t welcome, given that trespassing is a crime. When such people refuse, that’s unfortunate, but what can the police do but arrest them?