I know you want to be a "nice" person. I understand that. And I'm sure that it made you feel all warm and fuzzy inside to stop and let a half dozen or so Wal-Mart shoppers out of the parking lot and into traffic.
During rush hour.
Friday rush hour.
On a green light.
Let me explain something to you. There is a department down at city hall whose purpose is to monitor traffic flows and calculate traffic light times and synchronization to keep things moving. It's not a perfect system, far from it, but they do their best. And then you performed your little act of kindness, not looking in your rearview mirror (you do know what it's for, don't you sweetie?) and seeing that you had SINGLE-HANDEDLY BACKED UP TRAFFIC FOR AT LEAST THREE BLOCKS!!! Hell, I'm just glad I'd opted to walk instead of drive and was safely on the sidewalk, out of the direct path of all the driver mental hate rays that were directed at you. Because the cars in YOUR block couldn't move through their green light because your stopped car was in the way, the cars in the next block behind couldn't move through THEIR green light, thus preventing the next block from moving ... y'see how it works? Chain reaction. And that was just how far I could see ... you probably screwed things up for the whole eighty blocks between you and downtown.
The thing is, the Wal-Mart parking lot exit is NOT an exit ramp or merge lane ... there is no requirement to take turns. Cars exiting the private property of a parking lot have no legal right of way. Really. Read the traffic act and you'll see I'm right. And, y'know, maybe it's better to that anybody stupid enough to try to use the exit that's only 1.5 car lengths from the intersection (instead of one of the two other exits on that side of the lot that would let them easily get into traffic without disruption) during rush hour NOT be allowed out. After all, time spent in their car in a parking lot exit is time that they aren't home, potentially breeding.
Think about it.