Working FOR you. If that means that you are their employer, do you give these guys medical coverage ? Now that would be scary.

And yeah, when it comes to downtown, those couriers are pretty bold on their bikes. At least in heavy traffic, vehicle speeds are low enough that they are more of an annoyanc than anything.

It is the guys pedaling down major streets (Mac Tr or 14 street etc.) and are sort of in the right side of the right hand lane, and most people in cars either don't have enough room to get around them safely or are too scared to try. Big line of traffic behind them.
In this scenario, the guy on the bike can't even see the cars coming behind him. IF a car was going to run him over, he wouldn't even see it coming, and couldn't avoid it.
Very low margin for error all around. A few inches could spell disaster (scratched paint or broken mirror) <I'm all heart I know.>

I fail to understand logic, if there is any. Maybe some day I will be so bored and out of things to do that I will check out a street-cyclists forum and ask. Don't hold your breath though.