[bastawhiz]

Right, airplanes and other forms of transportation exist. But those 4000 people aren't there for a single 24 hour window (as most of them aren't). The point is that it's a huge number of visitor-days in the most conservative case. More visitors for more days means more burden on the city.

And by your numbers, assuming cruise ships dock for roughly the same amount of time as the median tourist visits the city, that means one 4000-person ship represents about 7% of the tourists in the city. Banning cruise ships is an awfully simple solution to take a meaningful bite out of a problem that local authorities clearly think is important.

[midasuni]

More days per person means less burden. Think of Cairo. If you visit for one day you are going to see the pyramids. 20 tourist-days = 20 visits to the pyramids. You likely do t have dinner out, as you’re off to the next photo op, you likely didn’t have breakfast either. You perhaps brought a packed lunch.

If you visit for 5 days you’re only going to see the pyramids one one day. 20 tourist-days means 4 pyramid visits, 4 Egyptian museum visits, 2 or 3 up the tower and various visitors to different museums and mosques, multiple meals out throughout the week.