Quality control wasn't an issue well into the 80's. I have a number of cards that are either oversize or undersize. The oversize ones are pretty cool, and were easy to spot in dealers boxes.
The first quality control issue I can recall was a packaging issue with 81 Donruss. Each pack had 11 of the same card and I think 4 others. The first quality control thing I can recall with the cards themselves was 88 Score. Part of the first run had poor die cutting leaving tufts of cardboard fibers sticking out but only on About the first third of the set.They replaced them with run 2 which moved the die cut gaps in about 1/4 inch from the corners still leaving tufts but in a different spot. Third time they went with a die cutting mat with no gaps. It was a big thing at the time....The second batch is actually pretty tough- at least as tough as a late 80's main set card can be
Quality control is still pretty lax. The production process has fixed some of the problems, but there's still plenty of messed up cards that get out including a few that don't meet the size.
Steve B