And then how do I get the ISP to advertise my service as being free to use, the same way they do for Facebook?
It's not much help that my clone is also free to use if nobody knows unless they go hunting through the fine print, as the initial assumption will be that it's a charged-for alternative.
"use all your social network apps without using up your data allowance", and then they show you a list of apps, but all social apps should be zero-rated and if they are not you can report it. Same with video apps, music apps, etc.
If you think this is so bad, then ask consumers if they like it or not. People here seem to put their principles before what consumers actually want or not. The job of the market is to serve consumers. Paying 3€ a month to have unlimited data on Facebook, Instagram, and WhatsApp is a sweet deal for 99% of consumers here I'm sure.
The market is created by corporations. It's job is to serve the corporations by creating the illusion it serves the consumers. That's why advertising / marketing is a thing.
Some would naively say that the market is created by the consumer, but you don't need most of what you consume, and you didn't even want a lot of what you consume until you were told it existed. (the term "you" is not necessarily referring to you personally here, but "the average consumer", on aggregate.)
The problem is not today but what the ecosystem will look like 10 years down the road under that system.
We saw it before and it wasn’t good. In short the carriers had control and companies that wanted access to consumers had to strike deals with the carrier, those deals as a result were very generous to the carrier (eg. they took 50% of revenue).
This is not good for the consumer over the long term.
Either you use the services that much and you pay 3€ or you don't and they get taken more simply out of your data plan. You pay more for unlimited use. If you don't need it, you pay less. I like it, I don't want additional social media services, I get to pay less.
It's not much help that my clone is also free to use if nobody knows unless they go hunting through the fine print, as the initial assumption will be that it's a charged-for alternative.