Should You Tip the Car Wash Attendant?

I frequent the car wash about once a week now that I have a black vehicle.

Recently, my girlfriend was with me when I rolled through the car wash. Because my car is black, I go to the "touchless" car wash and at the end of the wash, a couple of people are waiting to dry off my car.

After they're done I always tip them a few bucks.

My girlfriend looked confused. Why was I tipping them?

I told her that I felt it was the right thing to do. I tip my barista and the waiter/waitresses, so why wouldn't you tip the car wash attendants?

Do you tip the guy at the car wash? Who else do you tip that might seem odd to some people?