//Fair enough if your family operated a formal booking appointments system//
You obviously move in different circles to me (or you have a different outlook to me). I don't visit anybody unannounced. Never have. It's impolite. Nobody visits me unannounced because they are too polite to pitch up on spec. Everybody I know operates in the same way.
In any case, if granny suddenly finds six people on her doorstep and they've turned up without agreement, they cannot be surprised if, at the moment, she keeps them outside. People who are stupid enough to turn up mob handed on their granny's doorstep will not worry whether it's legal or not to do so. They'll do it anyway. That's why a great deal of these restrictions are completely unnecessary. People who are intelligent enough to make informed decisions for themselves will make the right ones. People who are not will not. But they won't be prevented from doing what they want by legislation.