Dealing requires an exceptional amount of concentration. You need to do every player's calculations faster than they do, while also controlling the game. But it's a lot of rote repetition, physically and memorization. Any person can be taught to deal over a week or two, if they can concentrate. It's just practice. But like suddenly driving a car on the other side of the road, it's hard to switch your automatic reactions. I grew up in a family of Vegas dealers, part of the genesis of my conversation with the guy who got me dealing poker. Blackjack is the easiest... mostly it's just simple additions, which you do the moment you deal the cards. Poker is much more about nuance and controlling and monitoring the game.

Would love to have a properly trained Vegas dealer weigh in here.