Even if they're not technically admitting guilt, paying that much money is taken as guilt by pretty much everyone. Don't know if Apple has taken reputational damage, but the damage to "Don't be evil" Google is severe for a lot of people where it can make a difference.
As for what's going to stop them, a recidivist is treated worse in the courts. They're now under the terms of a DOJ consent decree; violating those will in theory be bad for them (it gets political, of course). The path of another class action civil suit like this would likely be much worse. Etc.
Even if they're not technically admitting guilt, paying that much money is taken as guilt by pretty much everyone. Don't know if Apple has taken reputational damage, but the damage to "Don't be evil" Google is severe for a lot of people where it can make a difference.
As for what's going to stop them, a recidivist is treated worse in the courts. They're now under the terms of a DOJ consent decree; violating those will in theory be bad for them (it gets political, of course). The path of another class action civil suit like this would likely be much worse. Etc.