Wash my own for various reasons.
I like to. I even wash my daughters or daughter in laws on occasions, usually sneak out and wash them without asking them...gives them a surprise.
I'm tight. I hate paying a tenner for someone to do something I enjoy...plus I'm tight.
It' a good opportunity to check tyres, pressures, levels etc.
I hate giving money to cash only services, car washes, taxis etc...i doubt 50% of it gets declared.
As said earlier, i dread to think of the chemicals that get used...many of the car washes I see, the concrete or paving is eaten away where the acid has washed off.