Just to add a bit of light into this from first hand experience.
Our valeters have a lot of cars to get through, both sales & service. They do a very good job (well sales cleaners at least) at clean the car and making it shine for a handover. But they key word there is clean.
I've napped one of the kits, although we use Supaguard. The kits actually costs us £20, as the stuff on ebay are just all spares, or diluted stuff with water. I think it's good, but as you guys have all said, it needs to applied properly, and allowed to dry.
It's not detailing, so doesn't require a great amount of skill, but still, with a lot of cars to get through it won't be done to they way we want it do be done, despite people paying anywhere between £200-£700 at some dealers.
I got paid 20% off Supaguard commission. If I could sell it at £700, we would make about £500 after warranty, the kit, and paying for it to be applied (yes, it still costs for all that stuff). So £500 profit all adds up. Our penetration on new cars is 90%, so if you're dealers doing 50 odd new cars a month, soon adds up.
The only reason which would make me go to a dealer is the warranty. Never had anyone need to claim, but I've heard it hard to do, and they never sort it.