Here's a little life lesson that was kicked down to me:
"Don't ever ask/command/order someone to do something that you would not do yourself."
Interpret how you like, but to me it means, "Get your hands dirty and appreciate what it takes to do a job before you delegate."
I tend to think that doing physical work, understanding what's involved, is educational, informative, and motivating. A significant part of the world does work with their body. It's important in having empathy for other "classes" (assuming your kid gets an "information worker" job). Related or not, it's important to also learn how to do a job you may not like well, to pursue excellence in one's work.
Of course, if there's no life-lesson, why not just cut out the middle-man and have a local chore marketplace where kids from all around the neighbourhood can directly bid on the contract to mow your lawn. (Mostly kidding, but that'd be somewhat interesting for people who don't have kids, and don't need a full-on gardener.)