This is true both in their inferior form of "British Parliamentery debate" as well as the various American styles, such as Lincoln Douglas, Policy, or Public Forum.
Naturally the most obvious explanation for the US beating the UK at something is that the US population is 5x ours. Another explanation is that outside of public schools and Russel Group universities, we don't actually have much of a culture of competitive debating or debating societies any more. None of the schools I went to had a debate club, despite being relatively good schools, and I never heard of any debate competition being held.
From what I've seen from US competitive debate, it seems to be surprisingly popular with minority students and seems to use a style of rhetoric and scoring that I'm completely unfamiliar with - seemingly sometimes rewarding speed or Gish galloping. Here, the debates that most people would be familiar with are most commonly judged by their ability to convince the audience and are more popular with well educated, upper middle class people.
We truly are two peoples separated by a common language.
https://www.youtube.com/watch?v=wqjHz9laqgU&t=368s
And debate between the Harvard Democrats and Republicans:
https://www.youtube.com/watch?v=sYLcpQQCjLE&t=1655s
I've never seen or heard of a debate like the one in Peter Schiff's youtube channel there, and it is pretty obviously being shared on social media for emotional effect.
While I have to admit I'm not a fan of that debate style, if you want to know the context behind it, there's an episode of Radiolab on the topic: https://radiolab.org/episodes/debatable
The short version is that it seems to have been a response and rebellion to what was already an arguably ridiculous style of competitive "debating": https://www.youtube.com/watch?v=0FPsEwWT6K0
You'd think that in a community of "hackers" that should value actual skepticism and subversion that people wouldn't fall so easily for obvious propaganda.
And if this was an intentionally extreme example meant to demonstrate problems with the format, then sharing it and citing it here seems entirely appropriate and even expected.
For anyone else curious, this is maybe a good read:
https://www.theamericanconservative.com/how-to-speak-gibberi...
It starts with the knee-jerk conservative anti-woke reaction, which peaks here:
> A reader in the comments suggests that these students should listen to MLK’s oratory and take a lesson. Absolutely. King was a master of rhetoric. That is the way to change minds. The teachers who are instructing these kids in this sort of thing are guilty of intellectual abuse, as are the CEDA officials who reward it.
But the updates after that, explain what is really going on:
> Rod, this post needs a serious correction. While that debate was ridiculous, it is entirely typical of what college “cross examination” debating has been for decades. The trend has been for (mostly white) debaters to talk about nuclear war in a debate about education policy, the environment in a debate about military policy, post structuralism pretty much whenever they feel like it, etc. etc. It’s a ridiculous form of debate but it isn’t some weird black thing. The reason these black students are debating like this is that they are competing, in a league with teams from schools like Harvard and Yale, that rewards this style of debate.
And the author is slightly magnanimous in his apology:
> UPDATE.3: To be perfectly clear, I concede that I was wrong to say that this team broke the rules of debate by refusing to address the topic, instead choosing to rant about racism, and to say that the woman who looked as if she were having a psychotic break (which she does, to the untrained eye) was doing anything wrong. I learned from readers that the Towson team’s bizarre display is actually well within the rules and the custom of competitive debate. So, congratulations to them, I guess. I learned something new today: Competitive debate is a completely insane phenomenon.