So at what age should a child be capable of thoroughly cleaning after a poo?

[FishWithABicycle]

Fully toilet trained for some time, but still coming come from school with horrifically-skid-marked pants because of not cleaning up properly after a poo if he has one during the day.

I've explained thoroughly what to do and why it's important but DS would rather do a perfunctory quick wipe, which doesn't cover all the area and is therefore unsuccessful but, in his point of view, does have the advantage of not having his hand near the yucky poo for very long. When I try to teach him how to do it better he will happily practice better wiping on a completely clean bum but when it's dirty he just doesn't want to do it.

Anyone got any advice? Is this just a phase? Is he just too young (nearly 5yo)?

We use wet wipes for my dc at home and I just try to prompt them to poo at home because we have had this issue when they have been at school

It comes off easier with the wet wipes but I don't think they would be very good at remembering to get them from their bags before going for a poo at school