No, most pre-1989 cards don't come straight out of packs as Mint 9 or Gem Mint 10 cards. Otherwise, there wouldn't be nearly the premium on them that there is now. The major culprit is normally centering, but print defects, wax stains, bubble gum stains, etc will all bring the card grade down or add qualifiers. If you want to see a $14,000 box of 1973 Topps broken and turned into $1,000 in cards, look at this link:
https://www.youtube.com/watch?v=Sbbb2iowzGo This is what busting wax can be like.
I had a couple of slots, and I think I got 3 cards and one of the wrappers. Centering got a little better in the 80s and much better in the 90s, but certain sets it's super rare to get a 10 from busting wax, like 1986 Topps with the black borders. That's why the first PSA 10 1986 Ryne Sandberg sold for over $2,000 for a $1 card. I recommend you buying the card already graded if you want a certain grade. Because mailing cards to PSA can be expensive. If it was easy, there wouldn't be as much premium for highly graded cards, because everyone would have already done it.