Remember that most of those small stores are able to do this by breaking the terms of service. Accepting MobilePay is NOT free for business, it's not even cheap. As a customers is pretty easy to spot, if the stores MobilePay number is just their phone number, they're breaking the terms of service, and you should pay cash.
I never said it was free, but depending on the service you want, it is significantly cheaper than having a credit card terminal. One of the reasons it’s cheap is because it tells your bank about everything you buy. We worry about social media, but it’s the banks that know what brand of hemorrhoid medicine I purchased last week.
I’m not advocating either solutions, by the way. I’m just pointing out a use case. I mean, I care enough about privacy to not use google or Facebook, and I still use mobile pay because it’s really, really convenient.
Not sure about the last one though because Visa/Mastercard seem to be extremely entrenched in the industry, as far as I can tell they have completely replaced any other debit card system.
EDIT: To your last point. I think the problem with fee's is rather that you need to convert currencies when you do global transactions. Banks could offer this at a loss but nonetheless libra has an edge here.
I use it a lot. It’s never been easier to collect expenses from board game nights, and when I recently bought the first Harry Potter book (in Danish for my daughter) I didn’t have to enter my credit card information.
I think that’s what Libre will be, only global. I don’t like Facebook, but if they actually succeed at this, they’ll become the easiest way to pay for things on a global scale.