Have them do it and then you "inspect". Abbie does the same thing, although she doesn't run out of the bathroom. This gets them in the habit of doing it themselves and ALSO gives you the opportunity to give them attention and affirm the good job and/or tips for doing a better job. Lots of times, I think she wants the attention but knows she can do it herself. I just ask if she needs help. Most of the time now, she says "NO".
In addition, I think sometimes they want the kudos for doing #2. Remember what a big deal you made about it when they first started doing it? Sometimes I think they still want that. I know Abbie does and she's going on 6. Even if she takes care of herself, she STILL wants me to see what she's accomplished. Besides, as a parent, I want to KNOW how much, the size, frequency, etc.
Once I'm there, I make my affirmation and then the hand washing thing is a HUGE deal to her. We wash our hands together (even if I didn't wipe her). This may consist of singing the ABC's (how long you should wash your hands), me washing her hands - I put her hands in mine and gently wash and massage them. SHE LOVES THIS! Sometimes even if she's washing her hands for a snack, etc. she'll ask me to wash my hands with her. A GREAT habit to get into and she values that time.
This takes the focus AWAY from the wiping and puts it onto them growing up yet washing hands and maybe singing together gives them some one-on-one time & attention. I think I value that time as much as she does.
Hopefully, your kids will always want your approval and you most certainly will want them to remember the little things you did together.