For a low-wage situation, the enforcement effort only has to be made once to set an example for the others. Also, low-wage workers usually don’t have a lot of options in terms of geographic mobility, so it’s pretty easy to find out if that malcontent Joe has gone to work for another local landscaping company after leaving yours and make a lesson of him.
Chances are that one of those clients you call will either tell your former employer, or they’ll be solicited by your former employer and spill the beans then. That’s the kind of non-compete I wouldn’t fool around with.
Which is a great solution you can use because you understand that such contracts are negotiable, and perhaps because you have some leverage in the negotiation due to your education/skills/talent/experience/etc. The only experience that the vast majority of people in the U.S. have with contracts are “take-it-or-leave-it” agreements where they have little to no leverage (EULAs act as a training device in that way).