Most of us are traveling on a highway once in a while, especially on a holiday, and stopping at a rest stop. Have you ever really looked at someone pushing a mop around on the floor or cleaning a restroom? Well, there they are in a thankless job for a probably minimum wage with no future promotion. And no tip jar. Many others get tips like a waitress or hairdresser and in other service jobs. There are tip jars on the counters in McDonalds.
Think about it. A few dollars given to them once in a while might not make big difference in their lives, but it might make them feel a little appreciated and able to buy a little something extra for themselves.