This Time with Alan Partridge

Although a middle class North American house is generally going to be larger because there is a much more affordable land in the states.

Not in New York City - I doubt the the Friends could afford that apartment in reality.

Having been in a few, well, yes, they are quite large. I spent two weeks staying in a friend's house in Houston.
The first thing I noticed walking back into our own house, was how low the ceiling was.

This is explained in the show - Monica is subletting it from her grandmother (illegally).

That is the difference between UK and US sitcoms.

Most of the successful UK ones have been based on working class settings with small or modest normal sized houses, nothing more than a 3 bed semi.

In the US they always seem to have massive detached houses, and tend to have more of a middle class set up.

There is of course exceptions.

What possibly made myself, and others assume the AP series were location shot, was that the sound often
matched what you'd expect. 'Boxy' in Alan's hotel room, slightly echoey in the travelodge reception. Perhaps, that's the key, fool the ears, and the eyes will follow !

Yes, the sound and lighting were very true to what you'd expect in those spaces. The lighting for Alan's room was flat and grey whereas the reception had an artificial warmth.

Generally sitcom sets are brightly lit as if it's a stage show.

At least it explains things like "Two And A Half Men is filmed in front of a live audience" (or whatever).
Some American sitcoms didn't need such an announcement though - Tim Allen's Home Improvement used its live audience both for its show and for the show-in-a-show Tool Time segments.

Mind you Home Improvement went to town on the set design and lighting, managing to convincingly pull off outdoor scenes that were all done in the studio. It did go on location occasionally but not very often.

I don't think entirely faked canned laughter sitcoms have ever really been a thing in the UK. Go back to the 50s, 60s and early 70s in the US, the majority of sitcoms were done that way. There were only a few exceptions like The Dick Van Dyke show and the Lucille Ball sitcoms. I think it was All In The Family that made studio audiences become more common over there? I think that may have been the first US sitcom to be shot on tape rather than film as well, which also became common in the 70s and 80s (then tape seemed to die out on US sitcoms again during the 90s).

Even in the UK the sitcoms that were done without an audience tended to be shown to one later, so it's still real laughter. I can only really think of some kiddy sitcoms (like Spatz and My Parents Are Aliens) that have genuinely used fake laughter over here.

Aliens didn't have canned laughter originally, it was added a few series in. Fortunately it didn't do a Mike & Angelo and get it added to the earlier episodes.

For some reason I was going to suggest Little Britain but I may be thinking of Little Britain USA - which may have actually benefited from canned laughter as it was hard to imagine by that point there was anything actually funny from it.

I was under the assumption Bo Selecta used canned laughter (I know it's not a sitcom, unless you count A Bear's Tall) especially considering some of the DVDs featured a laugh-free audio track.

Great news.