There is assembly and then there is set-up. The bikes come in a hug wooden crate. The front wheel and fender need to be assembled, one turn signal bolted on and a battery installed. You can teach a monkey to do that.
The setup is the real key to a good bike. When we were selling iron barrels which could be problematic given the adjustments etc that needed to be made, you could tell the assemblers from the set-up people.
We had dealers whose customers had trouble all the time and dealers whose customers NEVER had trouble. (Vince is one of the latter).
Moving on to the UCE bikes there is nothing to adjust except the chain. But a good (or even decent) dealer will touch every last nut, screw and bolt on the bike to make sure they are tight, no pinched wires etc. They will check wheel alignment, tyre pressure, detail the bike etc. They will then ride the bike. I don't mean around the block but several miles at least. After the ride if anything shows up take care of it and then deliver it. The owner should never be the test pilot. A good dealer can say with total confidence that they know the bike is correct for the customer
We find that the entire key to a happy customer lies with a dealer who sets the bike up properly, gives the owner good instruction etc.
A dealer who is actually doing a "prep" job and is not just an assembler should be paid for his work. You will thank him every time you get on the bike.