I wasn't going to say anything, but given the comments above, I decided I'd jump in, too.
We all need to learn one important truth: gifts are only gifts if they are freely given, without strings attached, without conditions.
When you detail your Dad's car, you are giving him a gift--or least, that should be your intention. You are not entering into a contract with your Dad--"I will detail your car if and only if you take care of it properly." You detail it because you want to give him something that represents your love for him.
I understand your frustration. The simple fact is, as others have noted, most people do not care about having a swirl-free car. They simply want a clean and shiny car. So spend two hours (not twelve) and give your Dad a clean and shiny car. Use a one-step cleaner wax. He'll love it. He'll love it because his car looks good, and he'll love it because you freely did this FOR HIM. And you will have avoided all the frustration you have so vividly described. Focus on what's important.
Dad's aren't with us forever. I lost mine two years ago. He and I had a difficult relationship, but I miss him more than I can say.
Al