Well their are many more legal ways to making money besides lawn care and having to worry about some $20lowballer. If you keep doing good work you shouldn't have to worry. I bet their thinking the same thing about other lowballers. If their equipment goes down or their trucks from not doing proper maintenance do you think its going to get fixed for free? Thats alot of lawns to cut for only 20 bucks to get that bill paid.
Everyday you wake up you have been given 24 hours. What you do with those hours determines how rich you will become. The rich work the hours you don't see.
Great Book: "Think and Grow Rich"