In those cases where the items are resold by unauthorized resellers, warranty is completely at the discretion of the manufacturer. Some outright deny warranty when they don't see a proof of purchase from an authorized source and others don't.
I think its this "at the manufacturer's discretion" bit that is creating a lot of confusion in the market.
For example, you can go to NP and buy a Seagate drive from any of the 100's of shops there 99% of which are NOT "Authorized Seagate sellers".
Yet Seagate (usually) honors warranties on those products regardless. They don't ask you to go back to the vendor you bought the drive from and give all the potential invoices in the delivery chain so that they can confirm the "original" source was authorized. A quick serial check is all that's required. This is how it should work for most items.
IMO, it shouldn't matter WHO/WHERE I buy an item from -PROVIDED- the item was imported by the manufacturer (not discussing Grey Market Imports here) with import duties/taxes etc. legally paid for by the manufacturer. So whether I buy it from a Croma Store or WS Retail or a 3rd Party Seller on Amazon should be irrelevant.
In any case, I think its a little unfair to expect buyers to keep track of which online site/sellers are authorized and which are not. My post regarding Sony and FK above is a case in point. Once I have seen that FK (ie. WS Retail) is an authorized Sony seller, why would I go back and check this info repeatedly before each purchase?
Sites like Amazon, FK etc. explicitly state that products sold by them are "100% Genuine" (even though this may not be 100% accurate when it comes to all 3rd party sellers).
The above statement and the "goodwill/respect/comfort level" people tend to have for these sites seems to affect buyers "psychologically" in the sense that they extend this "100% Genuine" to mean that items purchased from these sites will also carry the same warranties that B&M stores provide for similar products. Many sites mention "Item carries 'X' years Manufacturers Warranty" for products they offer which further reinforces this belief...