I'll tell you why.

True event.

Back in the floods of 2004, right about as the river is about to crest, a guy comes to the check point with a Kayak on his roof, and demands that we let him through, he's a resident, he's going to check on his house, which we know is already under water.
There's leaking 800 gallons propane tanks and whole trees and oil and paint and swearage in the water, it's a mess. The river is running at about 30 MPH, FAST and the shoreline is collapsing in places.
But he's got ID, his home is on the river. We let him through.

Exactly 14 minutes later, we get a 911 call for a water rescue. This dumbass got 50 yards from where he put in, got pushed into the top of a tree, was stuck and the water is still coming up. He managed to call 911 and then dropped his phone in the river.

So me and two other guys end up in a boat, with the bow facing upriver, throttle nearly wide open just to hold us in place under him. In case we lost engine, we had a 600' line secured to the bow and a crew up on the rapidly vanishing shore ready to pull us back up with an engine if needed. It was a fast rescue - we cut the limb of the tree he was stuck in with a chainsaw and let him drop a bit into the boat, but we were mad.

Later that day I realized we were also idiots for letting him through, because we will not ignore a call for a living person in distress, so the only other option we have is to not let them get into distress.

The point is this - in times of clear and present danger the normal rules of freedom are - supposed to be temporarily - suspended. Mandatory evacuations are difficult to do, and nobody wants them. But when they happen, they mean mandatory.