Marketing can increase the size of the market. Making deals with other businesses can too (they pay a fixed monthly fee and get unlimited washes for all their cars, etc.). I used to wash my car myself but the automated car wash is so convenient I just go there instead. There's also a customer service aspect. I used to go to a more expensive car wash because the employees there were really friendly and at the other one they weren't.

Then there's the business aspect of starting this sort of business: deciding on what location is best, whether it's even a good business to start, etc. This is one area where people who want to be tech entrepreneurs are handicapping themselves and people who just go into business to make money do better. Lots of people think, "I need to start an AI startup" or devops, or whatever, instead of asking what opportunity is best for them.