This is not going to work. The governments will create millions of fake identities to spread their propaganda, same way as they are making fake passports for spies.
At least I have some say who is screwing me when my government is democratically elected (to whichever degree of democracy you have).
And that's for morally ambiguous cases where the justification is popular and well established things like crime fighting, child porn and so on.
We don't know what will happen in future, but given the story so far, the chances of these companies saying to governments, sure, have 500,000 free accounts so you can spam our users with incompetent political propaganda, is virtually zero.
The chances that they would comply with future government requirements cannot possibly be "virtually zero."
For Google and PRISM, I'm sure it won't change your mind, but I worked there at the time and the reaction was genuine. If there were people inside the firm who knew about it at all it must have been a very small group of spies/double agents, and such people were never detected despite a thorough search. Given that it was all based on fiber taps done by telcos though, it's not clear why they'd need any insiders. The assumption of formal cooperation was based on the phrasing of one or two sentences in some leaked documents, but the way the whole thing was set up didn't actually require it so, what those insiders would have been doing was a bit unclear.
Anyway, this is all by the by. We can't know what will happen in future. But if they won't budge on E2E encryption then it seems unlikely they'd be willing to bypass anti-spam measures, which is far more detectable, far less justifiable, and probably doesn't fit within any existing laws.
Do you have any experience with how things have changed over the last few years at Google?
I have a friend who said that 2016 was really a turning point in the culture. Prior to that most people were all about liberal values like free speech, and user freedom, but in the last 6 or 7 years it's become very "moderation" or "censorship" friendly (depending on your views), including for things like OP topic. On the plus side he has said that privacy is don't that used to be an after thought of anything, but is now in the cultural zeitgeist, do it's not all bad. Do you have any experience you're willing to share on that?
I don't agree that privacy was an afterthought before then. There were a lot of internal controls and privacy considerations had been a part of the design process even when I first joined in 2006. Of course the level of effort ramped up over time as the company grew. The primary constraint then as now was simply that most users trust tech firms, don't include them in their threat model and will reject even tiny amounts of inconvenience in the name of privacy. So that really heavily constrains what can be done. For example it kills most attempts at proper end-to-end encryption, leaving us with this sort of strange pseudo-e2e-encryption that's more a legal hack than anything serious (the company that supplies you with the encryption equipment is your adversary, which makes no sense in any classical conception of cryptography).
Who said you had to choose between these two scenarios again? It's so bizarre that people see government as an oppositional force to government contractors operating under government charters.