Even the cheapest herpstat doesn't have a mechanical relay, which in the same situation could fail on the On position as well.
I have seen too many times that when I say all I have used are the 100+ dollar thermostats, then go to the next guy who says you don't need to have one then, just watch it carefully. they walk out of there with everything but a thermostat (which there are herpstats for sale there), so I can only assume they choose to use nothing because of the price and reassurance of the other vendor doing anything to sell his snake. While I can say I feel better because thats not what I told them and didn't sell to them, that animal still went home with them. I'd much rather have a bare minimum package that doesn't shock them and deter them from using it at all.
Looks like the johnson thermostat requires some wiring, I don't really want to put that on the average person.
It's easy to talk down about the hydrofarm, its not proportional, no night drop, no mechanical safety, no other features at all pretty much, but if generally people are having success with it, I don't have a problem putting it out there as an option. At 33 bucks shipped on amazon I might order a few and have them on hand, not even advertise that I have them ( my buddy who sells the herpstats wouldn't be happy with me anyway lol), but if someone is about to walk out of there with nothing, offer it to them.