This isn’t a minor violation. It’s completely, unforgivably, obscene.
I think you’re being a little hyperbolic here. They aren’t rounding up people and arresting them for pulling their phones out of their pockets. The article literally says-
It is not enforceable by police – officers could not stop or fine people scrolling in the street because there is no national law against smartphones – but the mayor describes it as an incitement to stop scrolling and guidance for limiting phone use.