Did the manufacturer had to pay or did Microsoft had to pay the manufacturer?
Manufacturer pays MS a Windows license fee for every system sold, regardless of OS.
IIRC, they could pay a higher fee per system actually sold with Windows, or a lower price for every machine sold, regardless of OS.
Remember Microsoft IP infects everything, from SDCards to EFI/UEFI.
Some vendors offer a discount if you buy the laptop with Linux instead. See System76.
Those vendors don't have a license agreement with MS. But Dell, Lenovo, etc do.
So vendors exist that do not have a license agreement with MS. I rest my case.
I already knew that, we weren't at odds. There is no "case"
The case is that there are indeed computers you can buy that are not, in fact, eating the cost of a Windows license, because OEMs exist that do not have those agreements with MS. "You pay for Windows when you buy a no-OS PC" is not true if said no-OS PC didn't have to eat the cost of a Windows license.