Because gangs fear the curfew

That right there should be enough to enforce a ban on the movement of regular folk. Gangs are out and about killing one another, so let's make it so nobody can go out.

That's some problem solving, I gotta say.

To see that people are calling for this preposterous edict to be permanently enforced shows just how far down this country has become. Keep giving away your freedom. Just don't bitch when you get pulled out of your taxi past curfew because you needed a gallon of milk.