This anecdote resonates much more than explicit sharing of costs, thanks.

I suspect this might be cultural, and not just at a country level. I wouldn't dream of charging a family member £5 a month for something, I'd either let them use it or not. But that may not be true everywhere. Between friends it makes a lot more sense, but as I said I've typically seen Netflix/etc shared in families not friends, probably because the lack of money changing hands makes it easier.