Get angry at the people that make policy, not the people that enforce it.
Sure, the IRS could be nicer. However, as someone who had to handle a policy enforcement role from time to time...I know the people I had to enforce policy on hate me, personally. However, I'm just enforcing policy. That enforcement is basically an email saying "No, disregard what X told you because Y is current policy."
People at the bottom usually aren't assholes "just because". We become assholes because people get angry with us over stuff we have no control over [unless we quit].