After running different size shops for 15 years(in '02-'05 I have 10-12 "people" working for me) I dont have this headache now. I was debating renting/buying a large decent shop a few years ago, but I decided not to. There are few reasons, but 2 are the most important: I prefer to focus on fixing someone's car and do a good job instead of focusing on his wallet alone. In today's environment it is [almost] impossible for a shop owner to be honest with the city, county FD, PD and to be honest with the customers at the same time.
Second, but not less important is the quality of the services a shop provides. Even if one is the best and most careful mechanic when other "people" are hired the quality takes a big plunge and the warranty return rate increases dramatically. This is true in most shops except very few that are lucky to have a few decent mechanics working for them.