[helsinkiandrew]

I think you can argue that the experiment wasn't representative of 'normal' coin flips.

On average, each flipper in that experiment flipped a coin over 7000 times, after that amount many people will have learned to flip in a comfortable way with less variance between physical action and force they use. I'd imagine that in that case the coin would more likely land with the same orientation.

I don't think this would be true if someone flipped without practice.

[fbartos]

I personally did 20,100 flips and I can assure you I have no clue how to control the flip. I centrally got much better at flipping and catching the coin in hand without dropping it---which takes some practice on its own.

(I know that there are techniques for adding the wobble to the toss, but I didn't study them and I have no clue how to do them. I think it is safe to say you don't discover them intuitevelly.)

[SamBam]

I think this is a great point. One flipper 7000 times is quite different than 7000 flippers one time, if the aim is to see whether there is an underlying bias.

[misja111]

I bet that with enough practice, you can learn to toss the coin so that you get a much bigger than 51% chance of landing it on the same side.

[rootusrootus]

I think you'd need more than practice. Most people would need a teacher. Just doing something over and over isn't automatically going to make you better. E.g. The old "10000 hours of practice makes you an expert" rule assumes deliberate practice. And even then, it's incorrect.