At least for your last point... ideally never.
Look, I understand the intent you have, and I also understand the frustration at the lack of care with which many companies have acted with regards to personal data. I get it, I'm also frustrated.
But (it's a big but)...
Your suggestion is that we hold people legally responsible and culpable for losing a confrontation against another motivated, capable, and malicious party.
That's... a seriously, seriously, different standard than holding someone responsible for something like not following best practices, or good policy.
It's the equivalent of killing your general when he loses a battle.
And the problem is that sometimes even good generals lose battles, not because they weren't making an honest effort to win, or being careless, but because they were simply outmatched.
So to be really, really blunt - your proposal basically says that any software company should be legally responsible for not being able to match the resources of a nation-state that might want to compromise their data. That's not good policy, period.
We have HIPAA in the US for health care data. There have been no disastrous consequences to holding people and organizations responsible for breaches.
It's important to occasionally execute or imprison a general to motivate the remaining generals. Rarely though.
> any software company should be legally responsible for not being able to match the resources of a nation-state that might want to compromise their data
No. Not the company, holding companies responsible doesn't do much. The engineer who signed off on the system needs to be held personally liable for its safety. If you're a licensed civil engineer and you sign off on a bridge that collapses, you're liable. That's how the real world works, it should be the same for software.
Incidents happen in the meat world too. Engineers follow established standards to prevent them to the best of their ability. If they don't, they are prosecuted. Nobody has ever suggested putting people in jail for Russia using magic to get access to your emails. However, in the real world, there is no magic. The other party "outmatches" you by exploiting typical flaws in software and hardware, or, far more often, in company employees. Software engineering needs to grow up, have real certification and standards bodies and start being rigorously regulated, unless you want to rely on blind hope that your "general" has been putting an "honest effort" and showing basic competence.