I’m in the business and I still cringe over towing cost. All you can do is tell them to call around and find out that you aren’t robbing them.
The other thing you can do is set a rate of xx.xx then offer an old age discount of xx.xx -10%. Then you have a cover for those who kick. You can “sneak” them in under the senior rate. “Oh what a nice guy you are!”

i have ave some customers that I know are always going to beat me up on price. I estimate accordingly and let them beat.