I did a garden a number of years ago for a friend. He said, no rocks, no trees, etc. Just clear grass that has been mowed. There were rocks, some tree roots (but no trees)... It took much longer than expected and beat my equipment up as well as me... He complained that I had drug some dirt out on the ends when I turned around... I politely told him that I expected that would get taken care of with the shovel he was leaning on while he watched me... never offered me gas or money for gas, never really thanked me. His wife thanked my wife. I did one other garden and the rocks did damage to my rototiller so stopped doing it.
I'm thinking it is a tax free cash business the guy is running at $75. Likely doesn't have much and is not afraid of being sued (nothing to take).