At some point we've probably all pointed an laughed at the kid on a leash (I was one!). One time I saw a toddler driving his mother nuts by hovering in the air on his leash at the bus stop on high street. We think it's funny (or wrong, possibly) because we associate dogs with leashes, not humans. However, rambunctious children are nothing new. "Leading strings" were used in the 18th century to keep hold of runaway toddlers. In fact, dog leashes are a rather new invention, so you could say that child leashes came first!
Oh yeah, and you know those adjustable gates you put up to keep children out of the toilet or from falling down stairs? The 18th century estate house had its own version of that too: steel bars across the fireplace. I think the flaw in that baby proofing is when the child touches the hot steel bars! I have permanent scars on my hands from when I decided to boost myself up the kerosene heater as a baby, no wonder I needed a leash!