Shhhh....it's a secret....well, not really
As a former laptop/desktop phone tech for Gateway Computers (yep the same ones that used to come in the cow spotted boxes) I'll let you in on a little secret.
HP most likely doesn't write the drivers for the hardware anyway (I know Gateway didn't and I can't see HP being any different) although they probably did write the horrendous Java interface for their All-in-One USB printers...it's a nightmare getting that piece of crapware to work again if the USB driver gets corrupted.
The only difference between HP's "OEM" driver and the driver from the actual manufacturer is branding tweaks to make it look like they wrote it (that is if they even bothered to do that)...oh and possible add some OEM bloat in the name of "enhanced functionality"....but they started with a driver from the hardware manufacturer.
Vary rarely do I ever actually download a driver from an "OEM" most of the time I go look for the drivers from the manufacturer.
Biting the hand that feeds IT
