There are lots of live programs today.
Sure sports programs have product mentions but it’s not the same thing.
I watched a few episodes of The New Tom Green Show back in the summer of 2003, and he had live commercials a few times. He would interrupt the interview, walk over to a table in the middle of the floor, and give a sincere (if wry) announcement concerning their sponsor (I recall jeans commercials the most), replete with piano accompaniment from their house pianist.
It was clearly a nod to the past, as was his whole show.
Posted too soon… :smack:
If you count radio, the Grand Ole Opry does this all the time; the announcer will read off a spiel concerning the corporation sponsoring that part of the show (usually Dickies, Cracker Barrel, and Goo-Goo Cluster). Whenever I listen, I find these announcements just as entertaining as the program itself (and oftentimes moreso), thanks to the announcers’ smooth locution and diction.
Live television is a disaster waiting to happen. In the good old days of live commercials, products failed to work, cute little dogs threw up while eating the sponsor’s food, dancers’ boobs popped out of their costumes, announcers forgot their lines and Lucy got drunk on Vitameatavegamin.
If I’m your basic sponsor who’s willing to plop down a couple of hundred grand for a 30-second spot, I’d like to make it as follproof as I can.
Live television is a disaster waiting to happen. In the good old days of live commercials, products failed to work, cute little dogs threw up while eating the sponsor’s food, dancers’ boobs popped out of their costumes, announcers forgot their lines and Lucy got drunk on Vitameatavegamin.
If I’m your basic sponsor who’s willing to plop down a couple of hundred grand for a 30-second spot, I’d like to make it as foolproof as I can.
Or like in live internet forums where people double post! 
Well, one could consider the Home Shopping Network and others of its ilk one long live commercial. But I suspect the real reason is that with commercial time so expensive, the sponsor wants to get the most for his money in terms of production values and perfection. I’ve been to a 2 day shoot for a 30 second commerical. The amount of attention lavished on this thing was far greater than for a 30 minute sitcom. And the thing only ran for a few weeks, until they sold out of the product.
Some educated guesses:
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Local production is typically “value added,” or free to the advertiser, in exchange for the airtime they buy. TV stations these days have far fewer people available to staff a live commercial shoot, so the sales people don’t try to sell it.
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TV stations don’t tend to have the same kind of filler programming these spots used to run in. I remember live commercials appearing mostly in old movies that would play on weekend afternoons and late nights, and in afternoon cartoons. Stations usually fill their schedule with syndicated talk shows and the like, and they just don’t have the available advertising space to infest a single program with constant live commercials.
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Before cable was as established as it is today, you could run a program filled with obnoxious live commercials and still draw an audience. Today, fewer people will sit through that.
Does Willard Scott still do those Smuckers spots on Today? The ones with birthdays of really old women?
Which brings us to the disaster waiting to happen that kunilou talked about. 
Radio still does lots of live commercials, like DJ’s going on about a Subway Sub for 15 seconds before the traffic report. Stern does long live commercials.
There are live commercials on TV, but just not the kind the OP is talking about.
Things like,
“The Dominos Half-Time show”
or Survivor letting someone sleep in the back of the Pontiac Aztec.
That’s more product placement than commercial, though.
And this is a problem?