I think your analysis is incomplete.

What does it cost to rent a chair in a salon? (what is the operational expense (opex) of the current method)

What percentage of time that the salon is open, is the chair in use? (what is the haircut operational time)

What percentage of customers don't use your chair because they can't get to your location? (substitution value of stylists in a free market)

What percentage of your customers are 'regular' versus 'walk in'? (opportunity cost vs monthly recurring revenue (MRR))

I haven't done the research but I could certainly imagine in places like the Bay Area where rents are high that this could be a better system for a stylist than the traditional one.

Agreed, all of that matters. Also, another big difference from Uber is that the vast majority of adults can drive, so their pool of potential drivers is large. Barbering is a niche skill and in many areas is regulated. I can't just download an app and start working unless I'm already a trained and licensed barber. Then I'd need to own or rent the van outfitted with the chair and other equipment. The scaling model is vastly more constrained than Uber.

It's only about 2x because their overhead is cheaper (no rent, only car maintenance).

But yeah, what you suggest is exactly what happens here in Silicon Valley. We have the haircut group that spends one day a week at eBay, one day at Google, one day at Cisco, etc. Same with the dentist and the car wash folks.

"Are customers willing to pay 4x or more for that convenience?"

yes have you been to an Afro Caribbean barbers before?

he is saving around 4 haircuts kind of money because he isnt renting a seat in a salon. worth it for higher end clientele who doesn't want to waste time driving to barber shop