Just happened to come across this. Here's an example of why copyright enforcement for music is a problem outside the entertainment world: Police resources were wasted doing work like this:

Late in the afternoon of Jan. 16, a SWAT team from the Fulton County Sheriff's Office, backed up by officers from the Clayton County Sheriff's Office and the local police department, along with a few drug-sniffing dogs, burst into a unmarked recording studio on a short, quiet street in an industrial neighborhood near the Georgia Dome in Atlanta. The officers entered with their guns drawn; the local police chief said later that they were "prepared for the worst." They had come to serve a warrant for the arrest of the studio's owners on the grounds that they had violated the state's Racketeer Influenced and Corrupt Organizations law, or RICO, a charge often used to lock up people who make a business of selling drugs or breaking people's arms to extort money. The officers confiscated recording equipment, cars, computers and bank statements along with more than 25,000 music CDs. Two of the three owners of the studio, Tyree Simmons, who is 28, and Donald Cannon, who is 27, were arrested and held overnight in the Fulton County jail. Eight employees, mostly interns from local colleges, were briefly detained as well.

Later that night, a reporter for the local Fox TV station, Stacey Elgin, delivered a report on the raid from the darkened street in front of the studio. She announced that the owners of the studio, known professionally as DJ Drama and DJ Don Cannon, were arrested for making "illegal CDs." The report cut to an interview with Matthew Kilgo, an official with the Recording Industry Association of America, who was involved in the raid. The R.I.A.A., a trade and lobbying group that represents the major American record labels, works closely with the Department of Justice and local police departments to crack down on illegal downloading and music piracy, which most record-company executives see as a dire threat to their business.

Kilgo works in the R.I.A.A.'s Atlanta office, and in the weeks before the raid, the local police chief said, R.I.A.A. investigators helped the police collect evidence and conduct surveillance at the studio. Kilgo consulted with the R.I.A.A.'s national headquarters in advance of the raid, and after the raid, a team of men wearing R.I.A.A. jackets was responsible for boxing the CDs and carting them to a warehouse for examination.

Of course, even within the world of entertainment copyright enforcement is a problem. Albums that are now considered masterpieces like Paul's Boutique could never be made today because of how expensive it would be to get permission to use all the samples. That's what these people were essentially doing and they were busted and put in jail because of it:

The CDs made in the Aphilliates' studio are called mixtapes - album-length compilations of 20 or so songs, often connected by a theme; they are produced and mixed by a D.J. and usually "hosted" by a rapper, well known or up-and-coming, who peppers the disc with short boasts, shout-outs or promotions for an upcoming album. Some mixtapes are part of an ongoing series - in the last few years, the Aphilliates have produced 16 numbered installments of "Gangsta Grillz," an award-winning series that focuses on Southern hip-hop; others represent a one-time deal, a quick way for a rapper to respond to an insult or to remind fans he exists between album releases. The CDs are packaged in thin plastic jewel cases with low-quality covers and are sold at flea markets and independent record stores and through online clearinghouses like mixtapekingz.com. A mixtape can consist of remixes of hit songs - for instance, the Aphilliates offered a CD of classic Michael Jackson songs doctored by a Detroit D.J. Or it can feature a rapper "freestyling," or improvising raps, over the beat from another artist's song; so, on one mixtape, LL Cool J's "Love You Better" became 50 Cent's "After My Cheddar." In most cases, the D.J. modifies the original song without acquiring the rights to it, and if he wants to throw in a sample of Ray Charles singing or a line from a Bugs Bunny cartoon, he doesn't worry about copyright. The language on mixtapes is raw and uncensored; rappers sometimes devote a whole CD to insulting another rapper by name. Mixtapes also feature unreleased songs, often "leaked" to the D.J. by a record label that wants to test an artist's popularity or build hype for a coming album release. Record labels regularly hire mixtape D.J.'s to produce CDs featuring a specific artist. In many cases, these arrangements are conducted with a wink and a nod rather than with a contract; the label doesn't officially grant the D.J. the right to distribute the artist's songs or formally allow the artist to record work outside of his contract.

Well, to stoke the fire on the other side. I'm the Police (band). I don't want any rappers, DJ's, whatever, using my recordings, altered or unaltered and then selling them. That's not art, that's theft. I created that music and don't want anyone to mess with it.

Sure, Paul's Boutique is a great album, and the story goes it couldn't be made today, but I created the music that was sampled. Why should I lose all say over what can be done with it because I wanted to share my 'art' with the world?