Which is a fucking enormous if. I'd bet at least half the people reading the post do have kids. Fuck, it's having kids that makes many dream of dropping everything and running away halfway around the world in the first place!
The deal is they have to be a certain age. I'm thinking around 6 years old. Old enough to not require 100% upkeep, but young enough to not have much else going on.
Kids pre-teen or older would rather be hanging out with their friends than accompanying their parents on their budget travel fantasy.
Of course it depends on the kids, but don't forget that at a certain age, spending a lot of time trapped with parents is the last thing a kid wants to do, even if (especially if?) it's on a bus across Laos, or whatever.