I have gotten fines from the IRS, and it was always because I missed something and it was my fault. Sometimes it took a little work to figure out what the problem was, and even called them up when I was trying to figure it out. The people were never rude and always helpful.
Was I happy with it? No, who really wants to admit they made a mistake and have to pay to fix it? No many people, but you know what? I sucked up my ego, which all it really was, and admitted my mistake and paid up.
For all the scorn people heap on the IRS, they do a very good job, especially considering all the crap they get from anyone who seems them as an easy dog to kick.