Why isn't all network content streamed?

Hello,
On my apple tv I use the cbs app quite a bit. I've notice and this may be with other networks as well that not all content is streamed live. For example when I'm watching cbs I notice that the Dr. Oz show isn't streamed and on our local news casts all sports segments or anything having to do with sports is cut out and there's just dead air while that segment is playing, same when Dr. Oz is on it's just deadair. Does this have something to do with legalities?
Thanks.