none of those shows were actually very funny. they relied heavily on studio audiences and laugh tracks to make them seem funnier than they were. they called it "sweetening" because if the studio audience didn't laugh enough, they would just add some pre-recorded laughter over it. one of the cast members would say something weird or in a very exaggerated way, and the audience would guffaw but it wasn't really funny. same is true for "funny" tv shows today. laugh tracks and live audiences aren't as popular anymore, but they mostly rely on things like irony and cringe situations to be "funny" instead of actual jokes or comedy.
United States