None of those are ubiquitous. I'm describing the network effect, making this quite relevant. Also, I'm pretty sure some of those do charge 30% regardless.
Apple takes 30%. Needing to enter only a password to pay for something (instead of a credit card) probably makes that worth it. Facebook doesn't even require the password.
Pretty sure they don't charge 30% - I know the guys behind half the list.
Facebook are starting from scratch with credits, these companies and others have millions of existing users who have existing money in their accounts. Facebook on the other hand have hundreds of millions of facebook users, not people topping up their credits to buy stuff in games. Most of their users don't even play games.
That doesn't make Facebook ubiquitous and it will leave people wondering why they can't use the balance of their other account in the games they play like previously, and it will leave developers eating a fee that is up to 22% higher than it was through 3rd parties.
Although some will 'win' and make assloads of money overall it's not a 'win' anymore than it would be if you could only accept Visa.
Apple takes 30%. Needing to enter only a password to pay for something (instead of a credit card) probably makes that worth it. Facebook doesn't even require the password.