I worked in one of those shops when I was in high school. I know we probably all say this, but I was one of the few that actually cared and paid attention to what I was doing.
My favorite story was when I'd worked there for about 2 years, a recently hired 35 year old aircraft mechanic school dropout finally talked the manager into letting him work the pit, which was usually my spot because I was the (18 year old) senior lube tech that preferred not interacting with customers. He then promptly ignored his training to check to make sure the oil filter o-ring isn't still on the block before putting a new one on. After the guy pulled away I saw the trail of oil going out the door, and out to the street, and promptly went into the office, called the number on file to have him come back. Fortunately he was headed straight home, and smelled something pulling into his garage and came right back anyway. He had about a quart left when he got back to the shop, and the undercarriage looked like Deepwater Horizon, only not on fire.
After work I followed the trail out of curiosity and it led me right to his garage door about 3/4 mile away.