You ask "Who defines necessary?"
Well, just for starters, my employer.
He says that it is necessary that I be at work each and every day. Doesn't matter to him if I have to drive a car, ride a motorcycle, fly a plane, take a boat, walk, swim, hop ,skip,or jump to get there.
When I ask him for time off to go climb a mountain, he says it isn't necessary.
So, we are the heart of it. You would be off climbing, forsaking your nice big screen tv, if only you had an understanding employer.
Dude,,get over it.