I understand your point and you are right, especially if over the long run it results in higher premiums and co pays. I've only experienced a T waiving a fee once, when I lost my debit card. I offered to pay her at the next session but she said no and told the secretary to waive it. I wouldnt let this go on, but I do believe that taking a higher co pay is more problematic than waiving one, since it's the T who ultimately takes the hit, not the insurance company and not the client. So while I wouls point it out to my provider if they were under charging me and would probably insist on paying, I don't think I'd take it any further than their office if only because it's a kind gesture on their part.