Empirically, human-flipped coins have about a 1% bias toward the same side they started on: https://www.ams.org/publicoutreach/math-history/hap7-fifty-o...

But why it says "favors heads ~51%"

Updated to "favors one side 51%".

What sort of uncivilized mook dares flip a coin with tails facing up? Preposterous

I feel like when I flip a physical coin it pretty much always lands on exactly the same side unless I flip it real wierd.