Infrastructure can’t bear it, only so many people can fit in one place. Also, a lot of these people, especially on cruise ships, spend exactly zero money at the place they visit, as they have lodgings and food on the ship, and are only there to sightsee.

IDK about taxing lodgings, but maybe there are too many hotels for the place? I’d guess AirBnB made it impossible to regulate the market by controlling the amount of permits issued.

I think a small flat fee is usually better at solving this, as you would need to get rid of the people who visit but don’t pay, but that might be hard to implement if you can’t close the place off like you can in Venice for example.