It may be a hassle, but many of them are making big bucks giving medicals--especially the certificate MILLS. I know of one Doc in Miami that works Monday through Thursday, 9:30 until 4:30, and does about 35 medicals a day at $100. $3500 dollars a day is not alot of money anymore, but it's not a bad life for him. For regular customers, he has a 5 minute evaluation, write the check, pick up the certificate, and you are out the door in less than 15 minutes.
Um, $3500 a day, four days a week, fifty weeks a year (assuming two weeks of vacation) would be $700,000 a year. Even if he worked half the year, how is that not a lot of money anymore?