What's definitely forgotten here is that TalkTV...is basically radio on TV, as outside a few hours, it's just a rebranding of TalkRadio where most everyone is in front of cheap Hisense TVs in front of microphones doing a radio show that's simulcasting on TV, rather than in a radio studio, and badly. That is why the ratings nose-dived almost immediately; outside the curious seeing what their radio shows and people look like on TV now and a few gets, that's all they have for most of their broadcast day. Yes, Piers and their news block is all traditional TV setup, but that's a vast minority of their broadcast day,.
You can't sustain a radio simulcast on television unless it's designed for the medium, or fills a niche, which sports radio shows set up for a dynamic video simulcast with plenty of touches to tailor to both audiences can do rather easily. But Pat McAfee has that energy to walk around and do much more; your average talker, they're just sitting in a studio screaming into a spit-shielded mic and yelling at their producer for three hours or like Mike Levin's setup, screaming at the camera and destroying VU meters for three hours.
With most morning zoos, you see how the sausage is made and it looks like five hours of a group of four people in a studio both sleepy and looking like they'd rather be anywhere else. Sure, there have been radio studio simulcasts that are appealing, but unless you were Rush Limbaugh, who had years of experience doing television and knew how to frame his studio, you're not only not getting people to pay for that, but not want to look at those people for hours on end because they all kinda forget they need more than just a camera in the room, but extra television production features like graphics and interaction.
The main difference between America and UK/Canadian and Australian news though, is definitely the regulations, where news is clearly separated from opinion and can't be used to tee up the next hour of discussion. There's also a respect for the full audience where going off on people needlessly is going to turn people off, as what happened with Sun TV in Canada. There may be loud complainers, but they have the newspapers to complain to, and the radio. They just haven't made a good transition to television.