Labels put that in because they know if there is an uncleared sample that they don't catch and the original author sues, they're going to be involved in the lawsuit. And between Joe Producer and Big 4 Record Label, who do you think has the pockets to pay the fines? But the producer is still going to be involved in the lawsuit. And he'll take some kind of hit if the suit is successful.
That's just wrong. I'd even say the opposite - in most legal situations, responsibility is not placed on the end user: it goes up the chain till you get to the person/organization with the deepest pockets. That's as a practical matter - but even as a policy matter, plenty of situations involve holding those involved prior to the end user.EXAMPLE:
Guns dont kill people. Men with guns kill people. The arms dealer is not reasponsible for the murder.
Window Tint laws state that your windows can only be as dark as a state permits it to be (usualy over 15%) But a cop will pull you over and you get the ticket. The detail ship that put the tint on your car will never get the ticket.
Drugs. Mikes car is full of coke, but he is not in the car. Derick is driving and gets pulled over, he will be charged with trafficking even if he proves Mike owns the car.
Internet. Internet companies provide services to use internet, including illegal downloading or identity theft. They are never charged in a criminal case of either of those acts.
In almost all legal situations, reasponsibility is placed on the end user. Even if the end user had no knowledge of a possible infraction of the law.
Gun manufacturers almost were held responsible for crimes, and under the current legal system, that case may have been successful had it not been for the manufacturers' strong lobbying. Cigarette manufacturers weren't so lucky and got hit with that multi-billion dollar class action suit. The 7-11 stores that actually sold the cigs weren't.
I don't know how your drug example relates to the point, but even there Mike won't get off. His car can definitely be seized by prosecutors.
ISP's have been sued left and right for all sorts of things involving the actions of their users. It wasn't till the DMCA that they were given legal immunity for contributory copyright infringement in most cases for the activities of their users. And still, Google is sued almost every day for stuff end users do - trademark infringement because Company A bought Company B's name as an advertising keyword, libel, defamation, etc.
As for the work for hire question - in that situation, you never have a copyright. For purposes of the law, the person who hired you is considered the author. Any infringement is on their hands (though if that happens, they may have contractual provisions in place that they could use against you).