Often at ports of call cruise ships are mixed with cargo vessels, and passengers are required to ride a bus to the port entrance. They are irritated because they have to wait for the bus and don't see the danger in walking through a working port. There was an incident in Hong Kong on Monday that demonstrates the danger, even if you're just minding your own business.
A truck driver had parked his truck while he was waiting his turn to be loaded. A container (those metal boxes you see stacked up that are the size of a semi-trailer) disengaged from the crane that was lifting it from the ship onto another truck. The container dropped about 40 feet onto the top of the waiting driver's truck, crushing it and killing him. The fire department had to be called to remove him.
And that's why the ports insist on the cruise passengers taking the buses. They can be routed way out of the way of where the work is going on, letting passengers enjoy the port squish-free.