Yes I think all kids should wear diapers when on a road trip because it will save having to hold in the pee when you can't get to a restroom.
I wish my parents would have made me wear diapers while on road trips but they never did although I once wore a diaper on a road trip as a kid and my parents didn't know about it.
I didn't have to hold my pee in which made for a more comfortable trip and I just hid a few extra diapers inside my clothes that were packed away so that I could get to them easily and change the diaper when needed.
The diapers I wore as a kid were those old Luvs plastic backed diapers with Barney on them and they were great for road trips.
Now I'm an adult and wear Northshore Supreme diapers and Abuniverse Super Dry Kids diapers or any of the other diapers from Abuniverse on my road trips.
I never have to hold in my pee again and can just pee whenever I get the urge.
I also now wear diapers all the time and no longer use the toilet for either peeing and pooping.
Diapers are the most comfortable underwear and the best toilet as you can wear the toilet and not have to stop doing anything or playing to use the restroom.