That makes me think. Could one make a remote inflatable vest? Basically, one of those vests they equip aircraft with, but with a remote control attached as well. While deflated, it wouldn't have a significant effect on buoyancy or encumbrance, so the child could learn to swim naturally. If one notices one's child in distress one could inflate it with the push of a button.
And when it fails, and a toddler dies, the lawsuit would be enough to totally bankrupt the startup. Simply not worth the risk. I like the idea of using reactive technology to improve the cruft of aversion-type devices though.
I feel like this is why Hovding says it's "not intended for people under the age of 15". It's not that it wouldn't work most of the time, if not "all but a single time" and are simply protecting themselves from a possible lawsuit.
What's to prevent a condom-like "99% success rate" as legal backing for "haha can't sue us if it fails because we didn't promise 100% success rate"? Even though, effectively and when used properly, they have a 100% success rate... it's just there for legal reasons to prevent lawsuits.