I've driven a cab a few times to make a living and a good portion of the drivers I came in contact with were in it only as a IRS tax front for whatever underground trade they had as their actual means of support (drugs, pimping, stolen goods, whatever).
I remember the first time I came in to pick up my cab while wearing a sport coat and slacks. I was asked by about three different drivers whose funeral I was going to. They may have made more off of their side businesses but I know I made better tips as a driver.
/end threadjack