Why does VP Kamala Harris not salute the military personnel while boarding Airforce 1?

As the VP she actually has no power nor authority, unless Biden is finally proven to be senile. Then the Dems will be able to "Back Door" the first Female President of color into the White House.

Because she hates America

Because she follows the rules, Regulations on saluting actually say no one in civilian clothes is supposed to salute

The President is Commander in Chief.   Presidents often recognize that role by saluting the troops.    The VICE President has absolutely no connection to the military,  there is no such thing as Vice Commander in Chief.   So in the total civilian role as VP,  they do not salute.    If they did, it would be inappropriate. 

You either choose too salute or choose not to.  Mike pence did, joe Biden did.

Protocol she is NOT the Commander of the Military...

She isn’t supposed to.  No Veep does

Presidents are the one and only CINC:  Commander in Chief of the military.

VPs are not in the military chain of command.  IOW, she's NOT allowed to salute the military.