I use to read stories about this when i was ~9 on yahoo answers thinking it was a myth. I believed it was a myth till a friend whom i trusted allot told me he had a friend whos parents had him wear on long trips and use them rather than pull over. They where not in the USA, in the USA at least in my area I'm nearly positive that your kids would be taken away for child abuse should you attempt it for those reasons and manner, but none the less it shocked me to learn there where legit occurrences.
The only occurrences of this that I can see that makes sense is bed-wetters on long trips that will fall asleep.
I and my cousins traveled allot when we were younger. even at ~4 years old traveling 12+ hours we never had any problems. we stopped a tun, it was to long ago for me to fully remember how often. Normally(may[legal disclaimer]) end up having to pull off and pee on side of road during one long stretch of road that has no bathrooms up north.
I had allot of close calls, but never had any accidents. I never saw my cousins have any either. I would of loved to of worn back then. even at ~9 reading on yahoo, i was like wish that was real
but realistically it would only be cool to life long ab/dl and very demeaning to every one else. We put allot of weight onto diapers in society being for babies, and we can't really deny it seeing as it's one the main reasons we wear them as ab's. So it's my opinion that it is wrong unless the child asks for it, and is totally ok with it, not a you must do this if you want to go on vacation.
on a random 12am side note, man i wish i could of worn a diaper/pullup past age of 3 and have a being diapered memory in my childhood, alas I do not.