Their assumption, and it's true for most people, is that you're going to watch something. If they don't put tennis on, you'll watch whatever they do show, even if it's arena wrestling. So even by watching something niche that they wouldn't broadcast anyway, you're stealing.
This probably isn't true for tennis, but it probably is true for a lot of things. So you may have a pretty good reading on the mentality of the networks here.
I'm not sure they're quite that sophisticated, though. I think they're reasoning is more along the lines of "I own that, I decide how and when it will be viewed!" Kind of a total war mentality, where they're even willing to shoot themselves in the foot to defend copyright.
I don't know much about copyright law, but this behavior does seem to run counter to the spirit of the law, which is to encourage the creation and dissemination of content by granting a "temporary" monopoly for the creator. In theory, this would expand the amount of content available to the public. But what I constantly encounter is the use of copyright to restrict access to content by limiting what I can view, see, hear, or read - as well as attacking the technologies that promote the dissemination of content because they are used (extensively, I admit) for copyright violation.
It's all gone so wrong. Because congress has shown a willingness to grant extensions to copyrights that were set to expire, and the supreme court has decided that copyrights with repeated extensions don't qualify as copyrights in perpetuity, it's hard to believe that the monopoly is temporary. For all practical purposes, it's permanent - and the copyright cartel is more than willing to use them to shut down the tech factor.
I do agree with PG that there's no turning back the tide. The computer will defeat the TV. But the temporary delay can be a real pain in the ass.
That's just one more reason they're going to lose. That assumption no longer applies because I'm not going to watching something I'm going to watch or play or make something.
