If he has ace face up and checks and sees a king he is supposed to flip it over, show his blackjack, and take everyone's money. He instead let them play the hand out as if he didn't have the king.

Minor point of clarity... it doesn't have to be a king... in blackjack, a 10, jack, king, and queen all have the same point value (10), so any one of them paired with an ace makes a blackjack.

If the house starts with a blackjack they collect the initial wagers from anyone who doesn't also have a blackjack.

Yes... and this is a net benefit for players who might otherwise double down or split without knowing they were already beaten. Some parts of the world take away this player advantage.

I thought tie goes to the dealer, so they collect from everyone regardless?

A tie is a “push” where neither the player nor the dealer wins. Everyone keeps their money (you keep your money and the dealer doesn’t pay you).

Except in some European casinos, which don't check for dealer blackjacks before play. Under those rules - someone may correct me - a blackjack outranks any other 21, and if the dealer has a blackjack and you made a 21 with more than two cards, I believe it's not a push and the dealer wins. I could be wrong, it's been awhile since I played over there.

They often weight the rules back towards the players in other strange ways, like, being able to double down at any time (even on the 3rd or 4th card), resplit aces, as well as surrender.