The average age for a child being able to stay clean and dry without accidents is 5. Yes, 5. American expectations for this are pretty unreasonable, probably because preschools won't take diapered children. Some kids really can't do it young, and it's a shame that parents and kids feel pressure about it. 2Es and kids with disabilities in general sometimes take longer, but nearly everybody gets there eventually.
If your child is anxious about it, I would suggest backing off the topic and using whatever works (disposables, whatever) for the short term until everyone is ready for another try. (Your matter of fact approach about "here's what it's for, we wash our hands afterward" was very good IMO. Matter of fact is always good for ramping down stress.)
DeeDee
