Thing is, the British public and a lot of other western countries have become pretty soft in the last century. Likely more so than countries that have mandatory national service.
I remember my Swedish mate telling me about national service. My Croatian mate remembers being told to run home from school and not stop. Said there were hand grenades being thrown into the street etc.
Even without having seen full blown war in their lifetimes, there are plenty of people in other countries that have lived with the threat of war looming, or at least have some idea of how to act from their period of national service - handling weapons, working as a squad etc.
Many Brits, on the other hand, can't imagine anything worse than lockdown. I think it's unlikely that we'd be fighting on the beaches, but if China got involved at some point in the coming decades we could be in big trouble.
The US are always overconfident but they couldn't win the Afghanistan war after almost 20 years of trying. I'm not sure sheer scale of resources are the be all and end all. Russia were still somehow outproducing the whole of NATO in terms of ammunition until about a month ago and are also way ahead in terms of general missile tech, as are China. They also have more nukes and we currently don't have a defence against their subsonic missiles like the Oreshnik.
We do have advantages in other areas like aircraft but people that confidently state NATO are unstoppable are fools. For starters, most countries haven't seen a war for decades so it's all hypothetical. Russia are battle hardened and can actually provably fight. And you can't ignore the fact that millions of Chinese people will happily step up and fight whilst half our population won't.