Except in the case of indies with multiple printings. They've had a lot of problems with that.
https://www.cgccomics.com/boards/topic/242463-ninja-turtles-differences-between-printings/
https://www.cgccomics.com/boards/topic/166562-albedo-volume-1-nr2/?page=4
CGC may be more likely than PGX to take responsibility, but if they don't, then what?
CGC makes mistakes too. No grading company is infallible.
I know someone who sent in a book around April of last year. CGC missed the fact that the first four wraps were duplicated. He even indicated it with a sticker on the bag the book was in when shipped.
CGC indicates on their website...
So, this book passed through 2 restoration checks and 2 gradings, yet the extra wraps were not noticed.
Mistakes happen. There is always a risk associated with buying a book that you cannot inspect yourself.