If they post something on Twitter, or worse, Facebook, they must also provide a copy of the post on their own website. Some kind of online government gazette, if you will.
People here overthink so much about this topic.
As the state or a representative thereof, yes; that's why public service is either run by itself or contracts to operators who must then abide by requirements (like no discrimination, unconditional access to information, social pricing, or similar provisions depending on your jurisdiction), that they would scrape the very day their activity became free market.
In France, even banks, a sector without a public actor in most countries, are legally required to open accounts ("droit au compte"). I don't mean _any_ kind of account, but at least one. On which banks naturally don't make a profit...
Google or Apple on the other hand, have no legal duty to let you in, which means in practice that they can lock you out of public services that they gate access to.
BTW: overthinking is how society moves forward :)
To live in our 'free' western society, you need to register your birth, get a social security number, and attend state dictated education.
Life in general is now gated, and if you do not abide by the rules you do not get the benefits of society. How is this any different to "you are not allowed to have it until you hand over personal data".