My almost 4 and almost 5 year olds do it for themselves but both sometimes still need help for icky poos. DD1 will call out for help and then say "You hold my bum open Mummy and I'll wipe"!! Lovely!

DD1 was at kindy last year and DD2 starts in a week, and I know the lucky kindy teacher and assistant check the kids' bottoms. Given that, I'd definitely be complaining that a childcare centre doesn't help the kids too. Other than it not being fair on the kids, its probably self preservation on their part so they don't have pooey trails through the centre.