I think PSA has been slowly implementing AI, but not in the actual grading of cards. For now, they have been using it as a means of "fingerprinting" cards to detect if a certain card has been graded before and just being sent back in for another attempt to get a better grade.
I think the only company currently using AI to grade cards is TAG. However, they have restricted the cards they grade to the modern era. From memory, I think the reason they gave for this is because older cards have more variables such as how they were cut from the factory or various other things that were harder to have a machine learn from.