There is a new UK petition:
"Make all UK Government websites free to access without mobile data charges"
This sounds like a great idea. I like it.
In practice, I don't know how easy it would be for a mobile operator to zero rate resources on shared hosting environments (CDNs, AWS, etc).
The ICO, for example, has a link on its website to YouTube (which is certain A Decision in itself), on subject access requests. I doubt an ISP would want to zero-rate YouTube.
@neil Back when I was in CDN, the way that mobile operators handled this was to ask the customer to ask/tell us to provide a set of dedicated IPs, only route zero-rated sites to those and commit to giving sufficient notice before changing those IPs.
In practice, what they got was a set of IPs backed by load balancers, so their traffic didn't go direct to delivery appliances, but the performance penalty was pretty minimal.
The customer, of course, paid extra for all of this