Why do blackjack dealers burn a card at the beginning of a shoe?

They do this to help prevent cheating, in 1942 in Vegas a group of hustlers tricked a casino out of 12.6million dollars because they distracted the dealer and changed the deck for one of there own with their order of cards so they almost always won.

But i got a question too, why not burn either 1, 2 or 3 card the dealers choice as if someone does this again then they could set their deck excluding 1 burnt card every time so they could do 2 at the start then ace then jack then they would always win too there must be some sort of other prevention system.