Apple is a brand name that contains no technical information, whereas GPT is a technical term describing what the software does. OpenAI cannot patent transformers or generative pretraining, so it makes no sense for them to be able to trademark "generative pre-trained transformer."
So a better analogy would be Apple trying to trademark Screen Time so that no other smartphone OS could name its usage-tracking feature "Screen Time" - you can't trademark a description of what the software does.
It doesn't explain why society thinks this is an effective and fair set of rules.
They also follow this up with "you have to aggressively defend trademarks just in case".
But GPT is already generate enough in its sector, so...
So I can apply for a trademark for Apple Cleaners or Apple Tax Accountant just not Apple Computers.
Instead of looking at the outliers that exist in huge corporations, looking at arguments in small businesses that don't have unlimited budgets generally shows a more even system.