Which comes back to the way a company uses the signs. Firstly letting cabin crew do their normal jobs at all, with the signs on, simply teaches everyone that they aren’t really to be obeyed. And secondly, having them on, unnecessarily, and for long periods, magnifies the toilet issue whilst also reducing the importance of the signs for most people. I’ve been on airlines that literally leave them on for the entire flight. Stupid.
There’s also a percentage of passengers who simply will not fasten their belts, no matter what. I guess they think the earth is flat too.