Damn, most of those are literally 10's, the one that got an 8 made no sense, it clearly was a 10. I think they are trying to get you to regrade the cards so they can make more money
I would assume as in most companies the people working on the grading floor at PSA has no stake in the company and doesn't see any of the company's profits. So it wouldn't make sense for them to hustle the customers like that.
People commenting those 8s and 9s should be 10s clearly have never graded with PSA before. Your chance of getting a 10 on a vintage is less than 10% even if that card is pack fresh. Vintage cards, especially gen 1, have all sorts of factory issues like print lines, off centering, edge silvering, and corner whitening, and it looks like those base set 9s all have some of these issues.