Personal accountability isn't meant to solve problems. It is meant to prevent them by forcing individuals to put something ahead of their own career advancement. In other words, it aligns incentives in favor of preventing problems rather than in favor of solving them - you can only be the hero who slays a dragon if there is a dragon.
The laws around medical malpractice don't fix it when doctors screw up, but they make it a lot less likely for the screw-ups to happen, since those laws force doctors to adopt reasonable standards of care.
My question still stands, when has that really solved issues if they aren't regulated? Personal accountability without regulations is moot, toothless and I don't recall any instance of it ever solving anything.
To me what you are describing is basically regulations. Personal accountability only derives from regulations because there are punishments, in that case it aligns incentives.
Democracies and republics create personal accountability through regulations, since there is no single boss and power tends to come from legislative bodies or the people directly - those people want to provide input. Dictatorships (which companies fundamentally are) do not need regulations and rule-making processes to have personal accountability. Instead, the CEO can determine if you screwed up and fire you (or the dictator can shoot you) if you did. The specter of being fired (or shot) aligns your incentives to "do the right thing" even if the rules are not well-communicated, although you are better at doing the right thing if the dictator tells you what they value and what they want you to do.
Regulations are only one form of personal accountability. Regulations, in theory, create uniformity and transparency. These can be good things. In practice, regulations are often selectively enforced, which leads back to the same situation as in a dictatorship, but with a formalized process of input for the dictator.
I actually disagree with you that malpractice lawsuits are examples of regulation. More often, when something goes wrong and a doctor is involved, there is an argument about whether the doctor was negligent or not. There is no fixed "standard of care" that is written down, only a set of practices that are known throughout the industry. Experts argue about whether negligence occurred or not. There are regulations that the experts can cite in their determination of negligence (some of those rules carry separate penalties too), but you don't need to have broken any rules to commit malpractice. This is a prime example of accountability without regulation.
