At what point does any business that uses water get shut down? Business being open is vital, that is peoples jobs and livelihoods. Peoples gardens however aren't so vital, hence the outdoor water ban.
Maybe if people stopped using the car washes, they'd see no point in being open, and close. Then you'd be happy (at the expense of those who work there, and own the car wash).
Also the article says that service stations are voluntarily shutting their car washes down at times.
So don't really see your point.