The first fines should be meaningless to the company. If the issue isn't fixed the fines should get higher and higher. If the company fixes one issue but there is a second discovered quickly we should assume they don't care about safety and the second issue should have a higher fine than the first even though it is unrelated.
Companies (and people) have an obligation to do the right thing.
What do you mean by "second issue"? A second instance of the same underlying problem, or a different underlying problem? The way you phrase it as unrelated suggests the latter to me.
It's pretty wild to jump straight to "they don't care about safety" here. Building a perfect system without real world testing is impossible, for exactly the same reason it's impossible to write bug-free code on the first try. That's not a suggestion to be lax, just that we need to be realistic about what's achievable if we agree that some form of this technology could be beneficial.
The courts get to decide that. Often it is a "I know it when I see it". The real question is did they do enough to fix all possibly safety issues before this new one happened that was different. If they did "enough" (something I'm not defining!) then they can start over.
The goal should be to make them appropriately cautious. Not careless but also not paralyzed by fear. Escalating fines have the property that they are self-tuning. They basically say "go ahead and try it! But if there are issues you have to fix them promptly"
Companies (and people) have an obligation to do the right thing.