Maybe because it's not as intrusive as Big Bang Theory's.
Big Bang Theory uses the traditional 3-camera format, but has a live studio audience.
I don't think shows use "laugh tracks" anymore.
Two and a Half Men and Big Bang Theory definately use laugh tracks, as the laughs are pretty much repeating.
Big Bang Theory definitely has a live studio audience:
If you wanted to, you could come out to LA and attend a taping to see for yourself. However, the criticism is common of his shows that the studio audience laughter is unnecessarily loud. And, FWIW, I don't even hear the laughter. Perhaps my brain is just tuned to ignore it.