Hi B.,
I also have a 3 year old. Do you know what is helping? He just started nursery school and sees the other kids going potty. Now he wants to wear real underwear and go potty like his friends. It is not perfect...but this has been great.
so...to apply to your situation. Maybe try to share with him when daddy or mommy or xxx goes to the potty. Let him know others do it and don't pressure him. Maybe eventually he will want to do what he sees others do...
Anyhow, I think if we relax a bit they do too. I am very high strung when it comes to health and safety, but with this stuff I try to relax.
hope this helps a tiny bit.
jilly