That analogy doesn't make sense. Volkswagen is a brand; PC is not. Every personal computer is, and always has been, a PC. That's why we differentiate between desktop PCs and laptop/tablet PCs in the industry. Macs are a type of PC. I know this; I worked IT in the federal govt for 20 years and there's is no name brand just called "PC."
What you're confusing for "PC" is specific name brands of PCs, with specific hardware. When they added PC to software designation back in the day, they were letting you know it was specifically for a personal computer; not a VHS, not a record, not a game cartridge, not a cassette tape, etc. That was the designation, and then there would be more details about what specific hardware/software was required to use it. (e.g. Windows 95 with 512 MB RAM, at least a Pentium III processor, etc.)
When Apple started marketing their PCs, they built their own unique system that wasn't compatible with other PCs, so they started pushing the Mac vs. PC campaign to separate their equipment from the rest, which eventually culminated in those Mac vs. PC ads many years later. Products started receiving a Mac label instead of PC, to show that they wouldn't be compatible with the rest of the PCs on the market.
It helped that the rest of the PC industry started standardizing their equipment, to be compatible across all systems. Macs stood out from the rest, by refusing to be compatible with other PCs and forcing their users to stick exclusively with Apple products. It was a very anti-competitive practice, preventing users from sharing across systems, and one of many reasons the federal govt never went with Apple computers; we need to be able to share data with a variety of systems across the globe.
But Macs still fall under the umbrella of a personal computer. They are PCs. Even if they prefer no one calls them that.
On a side note, the EU just forced Apple to standardize their cables to USB-C, so they're getting rid of their Lightning cables and finally joining the rest of the world in cable standardization. But they'll fight tooth and nail to prevent any other changes. They're still fighting against Right to Repair laws, as they want to force you to return to them directly for any maintenance.