Live television isn't. Not in the United States, anyway.
Almost any television program said to be live is actually working under a seven second delay - this allows the television stations a bit of breathing room to comply with FCC obscenity and broadcast rules so that, for example, a screaming FUCK can be effectively bleeped over before anyone actually hears it.
The two exceptions to this rule were Saturday Night Live and major sporting events, which were broadcast without any delay whatsoever. This has gotten the networks into trouble before - Sinead O'Connor's desecration of a photograph of the pope on Saturday Night Live almost cost them their totally live status, and Ashley Simpson's lip syncing screw up this past October was embarrassing, but extremely funny. After Janet Jackson's naked breast became the focus of national scrutiny, petitions were put forward to add a delay to sporting events as well. This didn't hold water with fans or the network and the proposal quietly disappeared.