I can assure you, life for an ordinary person like myself life is much more comfortable in the United States than it is here, your money gets you a lot further.
Yes, more than a century ago. The UK is now one of the most densely populated countries on the planet, with many big towns and cities, towns and cities = heat
Sweeping generalisations. It depends where you live and how you spend your money. Living in the Berkshire/Oxfordshire region for much of my life, it is an expensive life, with property prices being such that i'm probably not capable (at least in the next 15-20 years) to move onto the property ladder in the area (at least, onto anything i would consider acceptable). Yet, move away from this overpriced commutting hub and there are some very affordable, livable places. Yes, the UK is expensive, but context needs to be applied.
An ordinary life in the UK isn't significantly worse than an ordinary life in the US. Define ordinary and it depends on the location.
Secondly, the UK is extremely densely populated, but it's actually still fairly rural. A good portion of the population still lives in "ruralish" areas. Suburbs or urban sprawl s much different here to other places. London aside, England has no significant cities globally with no large populations. It's really exaggerated how many people live in the city city.
Korea ... now Korea is densely populated. Smaller land mass, smaller population, but it has an astronomical % of it's population living in a few cities that are extremely close together. Those who live in the countryside aren't rich and they aren't overwhelming in numbers. Meanwhile, the UK has considerable wealth living on the verge of or outside the cities.
Finally, the UK has an extremely mild weather system. Why people moan about it i cannot comprehend, it's literally almost perfect. The Korean weather is just as cold, if not colder in winter, and exponentially hotter in the summer. You can argue that hockey isn't prevalent in the UK due to the absence of strong winter weather, but towns and cities = heat certainly isn't a meritious conclusion to anything.