Down here in NW Florida, "grunting" worms is big business. Folks go out into the National Forest at daybreak and work for 5-6 hours collecting worms. You drive a stob in the ground, then run a steel leaf spring {or something similar} over it, making vibrations. The worms come to the surface and everyone picks them up. You sell your worms to a dealer, and they pack them in cups and sell them to baitshops. Most baiters ride to the woods in vans or trucks with camper shells packed as full as they will go. It's almost two hours from where I'm at, so you have to leave about 0330 to get there at daylight. Each person has to pay a few bucks for the ride, so the truck guy makes pretty good money.
I've never grunted worms professionally, but have done it plenty of times for my personal use. Many of my school mates did it way up into their 20's. Lots of folks do it their whole life.