Vehemently disagree. Clearly the laws do as well given the "Prior results do not guarantee a similar outcome" disclaimer.If your lawyer, that you have paid for legal advice on the subject, tells you "that shotgun's fine with a 16" barrel, no need to pay for a tax stamp" they have committed malpractice. That doesn’t get you out of your prison sentence, but you *should* be able to sue them for a hefty sum for the faulty service they provided.
Malpractice is like an implied warranty. If someone sells you a bad product, they are liable. That goes for services too.
If someone screws up a brake job on your car and it leads to an accident, they are liable, even if you were the one driving. That's how it works.
Part of what you're paying them for is their assuming a measure of responsibility.
The only spot I would agree on is with the mechanic, as they are actually taking an action.
"If someone sells you a bad product (Like an AR-15) they are liable (if say, you shoot up a place.)" Danger Will Robinson danger.
If a lawyer gives you bad advice...do not continue use of their services and spread the word. That's how the free market works.