According to a recent CRYPTO-GRAM issue from Schneier, it's in Meta's interest to push these regulations as their product isn't an OS. Their competition (Apple/MS/Google) are OSs though.
There are also state actors at play here who would love if computing without ID became a very niche thing to do. Obviously their top line would be "fighting terrorism" and "saving the children" but in reality we've seen how these organizations (ICE, NSA, etc.) abuse their power and spy on people without warrants.
tl;dr: there is much more at play here than Facebooks interests alone.
One example of this was last year when high-profile apps like Candy Crush Saga and Clash of Clans were found to have privacy policies on their websites restricting users to 13+ so they could track and advertise more while their Android and iOS apps were designated for all ages so they could get more downloads.
It seems like a more lucrative path to go down even if you lose the under-18 crowd gambling / watching ads on your platform.
Because meta will not have to spend real $ to add/support age verification, plus they get to point the finger at someone else for age issues.
This is the real benefit to Meta/FB/etc. that many seem to overlook. Meta/FB/etc. are already staring down a lot of court cases related to "addicting youngsters" to their product (and potentially a lot [i.e. billions of dollars] of payout for settlements or penalties in cases that side against them).
But, if they can get the government to mandate that the operating system is responsible for verifying a user's age, they get to avoid liability (i.e., more billions of dollars) for serving anything from their properties to an underage user if the OS tells them that the user is "old enough" for whatever they served. So long as Meta follows the law and asks the OS "is this user old enough" and if the OS replies "old enough" then the liability for mistakes in the age identification shifts to the OS provider and away from Meta/etc.
The part that is odd here is why Microsoft, Apple and Google (the "OS providers" truly being targeted) are not massively lobbying against this due to the legal liability risk that Meta is trying to shift over to them.
This is likely because of Zuck's testimony in the very recent court case where he testified exactly that the "best place" to do "age verification" was in the operating system.
This was but a few weeks before all these, largely very identical sounding bills, suddenly started appearing in state houses across the USA.