"The fact that the biggest criminal fine in US history is < 2.3
billion, when companies are worth trillions (Apple market cap is 2.3T),
should tell you a lot about the actual regulatory power of the
government against big players."
This is graft.
The actual story runs something like this: in the back room players agree on a bribe in return for whatever service, and the judge is subsequently informed that they need to rule guilty.
Perhaps they get a little clever and fudge the evidence instead of informing the judge, but either way the trial is rigged.
The money is then funneled to the agreed-upon recipients, typically by manipulating procedural outcomes. It's very easy to guarantee because the recipients and system massages are planned beforehand.
Some of these fines are routine. (Probably not this one.) Essentially they're the firm paying off the regulator for not writing any genuinely restrictive rules. The government can most certainly shut down these players, but where would they get their bribes if they shut down all the billionaires?
Perhaps this one in particular is the payment for approving Pfizer's vaccine. If the regulator ran out of graft sources, they would promote vitamin D instead. You can tell because they're not drooling morons who can't even tie their own shoes. Vitamin D is not only effective against one coronavirus variant, but all viruses, and bacteria, and even body odour, being as body odour is largely bacterial. The side effect is (largely) better health, rather than shakes and aches and occasional death. However, vital amine delta is a cheap commodity, and Pfizer can't make billions off selling a few extra doses, and thus can't/won't bribe a regulator to promote it.
On the plus side this means the peasants are made even more sickly, and aristocrats, who don't need to be told how to manage their own health, look even better by comparison. Although less able to breed due to the disease, peasants still breed too much, but in the long term that's a problem that fixes itself.