The Importance of Dubbed Laughter.
I've read that when dubbed or canned laughter was invented the ratings of comedy shows went up.
Sketch comedy needs some sort of laugh track but not a phony baloney one.
As good as Fawlty Towers was it has a laugh track. It could probably get away without one but it would need a musical score and it doesn't have one.(at all).
Over the years of having watched The Benny Hill Show , The Two Ronnies, The Paul Hogan Show for example I came to this conclusion of which I may be wrong.
They have an intial episode with a studio audience. That episode I believe has the "STAR" doing a series of monologues and maybe one or two simple "live" sketches.
From that they have cutaways to as studio audience for the start and end credits only.
This smoke and mirrors approach means that this is the only time a studio audience is necessary but implies that audience was there for all 6 or so episodes.
It also implies that audience saw every sketch so that makes the dubbed laughter seem real.
And most importantly sketch comedy is a very hard sell without dubbed laughter.