Whose cause? I think the government already has our IDs, given that they issued them.
Governments don't necessarily have the connection between your ID and what you do online, though, and some governments are known to massively buy publicly available data from data brokers to circumvent existing laws. By "some governments" I mean the US government, by the way. That's not a conspiracy either, it's well-documented.
The government isn't typically facilitating the check. In order to verify your age, you will be required to hand over your ID to a third party, who's privacy and security practices are likely: "Trust me bro."
Seeing as how these companies get hacked all the time, (https://krebsonsecurity.com/2026/09/fbi-probes-service-selli...) , I don't think it's unreasonable to resist this.
Furthermore, I think many folks have reservations about requiring an ID checkpoint to utilize a computer. Obviously it's not that bad yet, but I don't think it's hyperbolic to state that the landscape is certainly trending in that direction, and it's absolutely not unreasonable to point out that governments and institutions to have a material interest in setting up access controls on who can and can't use the internet (read: participate in society).