Are insurance companies fair to their customers?

I don't' get how my sons insurance works. Per the company they cover XYZ, but then I get a bill for Y! Come to find out it has to do with coding that the Drs office did. I deal more with that than anything else. My son broke his arm and I had to bring him to the urgent care place. That visit was covered, but not the full cost of the brace & sling. Then - since they can't pu cats on anymore - I had to take him to the orthopedic. So far I haven't gotten a bill for that. On nice thing, his orthopedic scheduled his follow up as a post-Op so we didn't have to pay even the copay for the visit. Even so, after putting out the 2 copays + the bill, I am wondering how much it would have costs w/o insurance. My husband had to go to urgent care a month or so ago, paid $80 and got 3 visits + sample packs of medication so he wouldn't have to pay for anything.