As a rule in the UK car dealers know very little about detailing, certainly to anywhere near an autopian level.
From my admittedly brief experience with high end dealers (BMW, Mercedes etc.) they are marginally better but again not autopian.
The mainstream are a joke. I know that the Vauxhall (GM) dealer where my brother & dad bought their cars pay a cleaner to wash cars on the forecourt and the products they use for PDI are, as mentioned here, either very harsh (like acid based wheel cleaners) or are designed to last until the point of sale only.
I deal with independent specialist dealers regularly (I sell them insurance) and since joining autopia I have started to take maybe a bit more notice of how they prep cars. Some have purpose built detailing bays and some use mobile detailers but generally all I see product-wise is either Autoglym pro range or Autosmart.
The latter are made purely for the detailing industry where speed and low cost are I believe primary considerations. I've never seen a DA buffer anywhere at any client, just rotary types.
Through my own poor experience of dealers being let loose on my car, I would NEVER let a dealer prep my car again - I'd rather have it delivered dirty than spend the first few months of having a new car trying to rectify bad prep!
From a cost standpoint, $150 (about £85) would be considered expensive over here by most. I've been asked by my GF's boss to detail his Merc ML and I've agreed but he previously paid a mobile guy £25 (about $45) once a month I think to wash, vacuum, wax etc. He stopped using him when he damaged the car and then revealed he had no insurance!
Car is in reasonable shape generally but it's probably 4-5 hours of work so I've told him that I'd be looking for at least double what he paid before (remember, I don't detail for a living but think I ought to do some jobs to pay for my autopian habit!)
We have a guy who does car cleaning here at the office. He charges £10 a car (about $18) for this
Pre-wash with dishwashing liquid (found this out as he sprayed the front end of my car by mistake - no mistaking that smell!)
Wash and rinse (shampoo make unknown)
Dry using synthetic shammy leather and spray wax (aerosol)
Tyres/trim dressed
Glass polished
Interior vacuumed
He manages to usually do 6-8 cars in a day. This is all most people will pay BUT they're doing it 3 or 4 times a month - personally if I let anyone else near my car I'd rather pay £40 for a good detail than £10 for a basic wash as above.
Sorry to ramble here!