I think there are companies that build/sell turnkey carwashes. I don't think it's very sophisticated to be honest. It's really just a couple of high pressure sprayers, some soap/foaming sprayers, and a track that pulls the car. It's all technology that's been available for decades. I bet there's a factory in China just pumping out car wash components.
You can buy them out of a catalogue, and if you need it in a building I think the building requirements are simpler than most other retail space. I used to work in the railroad industry and even train washes, a much rarer thing than car washes, were purchased practically as turnkey things.
There's a lot of unseen plumbing there, though, mostly underground tanks to handle storing graywater (cities have fairly stringent rules about discharge rate, so you have to store and slowly release a lot of water over time), plus (increasingly these days) reverse osmosis systems and graywater scrubbers for recycling. Most of the cost there goes into construction, not components, of course, but it's considerably more complex a build than older setups.
