"[my car has a mirror on the left side. I can see stuff back there]". Excellent logic, so you know when there isn't a nut on a bike overtaking you, and you can open the rear passenger from the drivers seat?
Cab passengers don't have rear vision mirrors to see when someone is going to be stupid enough to run into the door.
The fact that you (may) be allowed to do something doesn't necessarily make it safe to do so, and does not mean others have to look out for your safety. You'd be allowed to pick up a red back spider, but are you silly enough too? It is obviously not a safe practice to overtake stationary vehicles within the area that a door can open to, yet cyclists continue to do so.
