Great Value is a brand too, happens to be Walmart house brand. But you still aren't right.
It's a matter of volume. Mass market stuff tends to be of lesser quality, or have a much higher failure % than limited production stuff, regardless of Brand or lack thereof.
The psus made for HP by Seasonic or Delta use the same components, same QC, same everything. Seasonic doesn't buy cheaper components just to put into an OEM psu, that's a ton of extra squ's, less discounts on bulk components etc, they come from the same bins. Seasonic doesn't do sloppy soldering or any less quality of manufacture, just because it's an OEM unit. The only difference is the platforms and circuits inside. You won't get the 80+ nor anything above atx standard...