If you check out the very earliest TV comedy, especially from the UK, it doesn't conform to what we now know as the "format", which was developed by people like Sid Caesar and the teams of writers who churned out the gag-a-minute scripts that we see today.
The Honeymooners, I Love Lucy, Dick Van Dyke, Mary Tyler Moore, the line goes all the way through to Friends and Everybody Loves...almost unchanged.
I watched one of the early episodes of On The Buses the other day, it was in black and white, and was probably the first two or three ever made. Awfully sexist, but at the same time very innocent. Women were "birds" or "ravers", very antiquated now, but in its time this was common currency.
There was a lot of character distinction in On The Buses, despite its faults. People had distinguishing personalities, unlike the American system which allocates cartoon "types" as though casting a kids show - the fat one, the jock, the funny one, the closet lesbian, the ditz, the fastidious one, etc, etc.
I've had umpteen shows pitched to me by US professionals (all absolutely convinced in their project's innovative qualities), and this is how all shows are developed in the States - virtually no character distinction, actors are just human devices for delivering lines.
Seinfeld did change that. It broke the mould in many ways, with solid and distinct differences in the personalities, and Seinfeld himself (like Batman) as the void in the centre compared to which the others inevitably are more interesting. Larry David, the genius behind Seinfeld, showed what he could then go on to do with Curb Your Enthusiasm, taking American humour to another level.
Look how British comedians see themselves compared to their US counterparts: Ricky Gervais went to the States to interview Larry David and Garry Shandling ("Larry Sanders").
David and Shandling pulled all the stunts - turning up late, making an entrance, and constantly engaging in a battle of "zingers", whilst Gervais giggled like a schoolboy. To the two Yanks it was war.
This illustrates the difference between the Brits and the Americans. In the US, comedy is taken very, VERY seriously. If your show rates, you live. If it doesn't, your career is over. For ever. That's why formulas are so crucial. It takes great courage for someone like Seinfeld to make a "show about nothing". It wasn't an overnight success, and nearly didn't make it to air at all, however, once it did, the network threw money at it, making a multi-millioniare out of Seinfeld, David and the main actors. Seinfeld need never work again.
Watch the early Steptoe and Son episodes and you wonder how the thing ever stayed afloat! Some of them are awful, but the solid characters and the excellent acting made the shows work as drama even if the comedy failed. That's where the US falls down. If the gags misfire, the whole show is a dud.
Look at The Good Life. Beautifully acted, the premise was sound, and Margot's character was rock solid. Yes she was a total snob, but she was never unpopular. She was actually very vulnerable, couldn't exist outside her own social circle, but loved her husband, loved her life and was a dear friend to Tom and Barbara.
Also, the series had the courage to go many minutes without the need to have a gag. The story, plot development and characters were created by people brought up on the theatre, whereas the American counterparts were the latest in a line that stretched back to Vaudeville, where if you weren't funny fast enough, a hook came across the stage and yanked you off.