you run a company distributing in singapore, you pay rentals and staff wages,
somebody buy whether from malaysia or usa want a RMA from your company when you didn't make 1 single cent out of it...even cars distributors wont do it with parralel imports
Car would be very different, because they can simply charge for the replacement parts and pro-rated services as long as the customer willing to pay for it(maybe like very rare car or parts). I dont think car manufacturers will give a sh*t whether you get your car replacement parts from the appropriate regional distributor or elsewhere as long as it fits and you are paying
But things like GPU the only things that can possibly fail is fan or pcb, fan replacement I imagine can also be simply charged per piece easily, but pcb repair/replacement falls under RMA which cant be easily quantified, and also I think largely due to regional pricings control/product manufacture laws in certain countries/etc, that manufacturers dont allow different regional distros to RMA products not from their region.
Anyway its not just simply about $$$ for GPU's, I spoke with a friend from a local distro before regarding typical GPU RMA procedures, and he said the reason why local distros are so anal about checking serial number/receipt to make sure its locally distributed product is because they had past incidents where they replace card for customer and then send the faulty card back to manufacturer to RMA, only to be rejected by the manufacturer because the serial indicates its not a SEA distributed product, then like I previously mentioned they're left with a piece of useless product.
If people are willing to pay I believe distros would be more than happy to offer RMA services for non-local products, but the problem's with manufacturers, not distro.