Right, so Bill Gates was given an "honorary knighthood" - as opposed to what? A real knighthood? It is not as if knights of the realm dress up in armour, get on their horses and go off and fight for the monarch.
"Real" knighthoods* can only be conferred on citizens of Commonwealth countries. America ejected itself from what became the Commonwealth 250 years ago.
* Of course, none of this nonsense is real.