Call me a skeptic but I kind of doubt that a comparison between US and UK pricing is remotely fair and unbiased. Your sleeping bag's price is influenced by a whole range of variables. it's not cookie-cutter.
U.S. minimum Wage is $7.25/hour, equating to about $15,000/yr for standard 40-hour workweeks. The UK's minimum wage is 25% higher than that at $10.00 per hour, with 38.5hr workweeks, equating to about $20,000 a year.
That's just the bottom...
I know people in the UK are taxed a lot more, but your taxes DO a lot more for you than they do for us. Much more of my tax dollars go into military spending than yours do, which means more of your tax dollars go into civic services, and on top of that, my health insurance comes out of my salary. Yours is included in your taxes.
On top of THAT, my education purchased in the UK would be tens of thousands of dollars cheaper than it was in the United States. I went to a state liberal arts college with my tuition paid for and I still owe $20,000 in student fees for my two degrees.
We can't even look at average salaries. because of the wage disparity in the United States, your lower and middle class take home substantially more of their wages than people living in the U.S. who pay for their own health insurance. Our top 2% most affluent skew our data so greatly, the United States places about ~10-15% higher overall in take-home personal income. But if you look at quality of life, property value, and access to essential services, the UK is ahead.
So, I don't have sympathy. I lived right outside of NYC for years and every single thing around the city is about 20-30% more expensive than stuff around Western Massachusetts. Right down to bottles of water. Why? Because the average wage is higher. Even the wages at the bottom were higher.
Every place is a microcosm. Every town in the world is its own economy. Comparing the two is like apples and oranges.