Google didn't pay that money just to bypass the formalities along the way to paying a fixed fine - they paid it in order to head off the possibility that they were going to face a jury trial instead of a bench trial, since juries are far more likely to vote in favor of much bigger fines than judges are.
I don't think it's about the fines, it's about the cost for Google to fight in court and perhaps setting precedent. It's often just cheaper to pay the fine.
The specific point of all of this was that Google wanted to avoid a jury trial, and the specific reason that they wanted to avoid a jury trial is because a jury trial is much more likely to end up with a much bigger judgment against them. A judge in a bench trial will follow established precedent to arrive at a reasonable penalty, while a jury can and often will essentially arbitrarily decide that they should be fined eleventy bajillion dollars for being assholes.
So their goal with this payment was pretty much exactly the same as the goal of the motorist who slips a traffic cop a bribe to get out of a ticket - to entice someone with immediate cash in order to avoid potentially having to pay much more somewhere down the line.
Except it's not a bribe. It's entirely above-board, the money they're paying is a fine. They're not "getting out of a ticket", they're paying the ticket.
They paid what the jury could have imposed and now they're skipping right ahead to facing the judge, they're actually saving the system some time and money.