Actually from the customer's POV, it does end at the bike shop. That's where you take your broken bike for any warranty issues. From then on it's the bike shop's baby. The customer has no recourse with the manufacturer.
Jur, read the warranty that you got with the bike. The Dahon warranty for example starts with 'Dahon warrants ...'. It binds Dahon, not the retailer. Same as a car warranty binds the car manufacturer, not the dealer that sold you the car. Problem is that there are two independent companies operating under the name Dahon and they do not clarify which of the two is bound by the warranty you get. It's odd.