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.