A large share of sitcoms are shot on a small number of permanent sets, in front of a live audience, with several cameras running at once. The format is a production method with specific advantages.
The audience is part of the instrument
Comic timing depends on response. A performer adjusts pace to the room, holding a beat when laughter runs long and pressing on when it does not come.
Without a room, that adjustment has to be guessed in the edit, and the result reads as flatter even when the material is identical.
Recording in front of people converts timing from a post-production estimate into something decided in the moment.
Standing sets make the week possible
Multi-camera shows use a handful of sets that are built once and left standing for the run.
That removes the largest daily cost of location work, which is moving equipment and people and relighting from scratch.
It also means the cast rehearses in the actual space from the first day, so blocking is settled before the cameras are loaded.
The week is built around rewriting
A typical production week runs from a table read through rehearsal to a taping at the end, with the script changing throughout.
Jokes that fail at the read are replaced before they are ever staged, and the version taped is often substantially different from the one written.
Few production formats allow this. It works because nothing has to be built, travelled to or scheduled around outside the stage.
Multiple cameras remove the coverage problem
Running several cameras simultaneously captures wide and close angles in the same take.
A scene can therefore be played straight through rather than repeated from every angle, which preserves the performance and the audience's first reaction.
It also cuts shooting time sharply, which is what allows a whole episode to be recorded in an evening.
Why the single-camera style took over anyway
Single-camera comedy borrowed film grammar: location work, no audience, and editing that can carry jokes visually rather than verbally.
That produced a looser, more naturalistic style, and it travels better to viewing that is spread across weeks rather than watched as a weekly appointment.
The stage format persists where the writing is verbal and dense, because nothing else lets a room of writers keep improving the material right up to the moment it is recorded.