"Who do you think is going to pay for the extra testing?"
The people buying the cheap crap. Once they've bought 4 different versions, none of which can do proper serial communcation, they'll either give up or, if they are lucky, ask. Then they'll get pointed in the direction of a reputable supplier of FTDI chip converters and automagically their equipment will start talking again.
Well, that's what happened to the research organisation across the road from us. They finally asked if they could borrow one of mine, since our equipment didn't seem to have a problem. Job done shortly after. Cost them 4 weeks and more than the price of a proper one.