Babysitter vs.Yard Boy

My teenage yard guy from up the street gets paid a reasonable $22 each time he mows my lawn, which inevitably includes moving toys and branches from the tree.  It usually takes him about an hour.

His little sister comes sometimes and plays with/watches the kids, often while I'm still at home.  She makes about one-third of what he does an hour.  In fact, my most prized Babysitter, of seven years now, makes a little less an hour than yard guy.  And I think I pay within the average (well, more for Babysitter!).

Do I love my lawn more than my kids?  Do I think mowing requires more skill than childcare?  Is it because I pay him by the job and her by the hour?  Is it because he's male?  Or is it because, following the professional rate, yard care people just command more in the market?  My professional lawn service previously was $25 a week, my professional nanny-service nanny was $19 an hour (plus fees for the agency).  

I'm not sure I like it, whatever it is, but I'm glad I don't have to pay my babysitter $22 an hour!