A huge component of compulsory (either by statute or de-facto as a result of adjacent statute, like mandatory insurance + requirements thereof) professional licensure is that if you follow the rules set by (some entity deputized by) government the government will in return never leave you holding the bag. The government gains partial control and the people under it's control get partial protection.
"oh I'm sorry your hospital burned down mr plantiff but the electrician was following his professional rules so his liability is capped at <small number> you'll just have to eat this one"
I would wager that a solid half if not more of the economy exists under some sort of arrangement like that.
I think the point is supposed to be that "following the practices and procedures that limit their liability" = "doing their due diligence to reduce risk in accordance with their credentialing body".
We generally don't hold people liable for acts of God or random chance failures. For example, malpractice suits generally need to prove that a doctor was intentionally negligent on their responsibility.
Everything in real life has quantifiable risk, and part of why we have governing bodies for many things is because we can improve our processes to reduce the risk.
It's not just following orders :) it's recognizing that the solution to risks isn't to punish the actor but to improve the system.
I'm not thinking act of god type unforseable event I'm thinking "everyone knows this is stupid and wrong and will cause a problem eventually but it's easier to just follow the rule than challenge it" situations because "if I follow the rules my ass is covered".
"oh I'm sorry your hospital burned down mr plantiff but the electrician was following his professional rules so his liability is capped at <small number> you'll just have to eat this one"
I would wager that a solid half if not more of the economy exists under some sort of arrangement like that.