In NYC and many congested areas a "door zone" can be just about anywhere on the road.
The one time I was doored was when I was taking the lane and a car stopped in the far left lane, in this case reserved for vehicles turning left, swung open the door on the passenger side of the vehicle nailing me hard in the left thigh as I passed in the middle lane at around 20+ mph. I was sent careening across another lane, hit the curb went over the handlebars and somersaulted onto a fire hydrant- it hurt.
Turned out it was a hitch hiker, who had been freaked by the driver and hurriedly jumped out at the light. I never was able to file for any claims for my injuries and damaged frame because the guy took off like a shot. But I learned a hard lesson- any time you are in the proximity of a car the door can fly open. It is one of a dozen things to be constantly on the look out for as you ride in traffic.