A human needs linear time as well. They'd need to examine one card at a time through the whole deck to verify something is not out of place towards the end. 

It's also easy for a human to miss 2 swapped cards in the sea of the other cards. 

Linear scan by humans is required for correctness

Yeah that’s true. Maybe another way to think about it is that when it comes to physical effort, a human can verify a deck is in the correct orientation (all cards facing the same direction) instantly by looking at a spread deck. Much faster than organizing a deck of cards manually.

Searchcaster