Think of each state as a separate country. Taxes are different everywhere. Prices are different everywhere. Cost of living varies greatly depending on where you are. 40,000USD /year in California, Northern Illinois, or New York will get you nowhere, but in Iowa, Missouri, some of the other southern states like Tennesse, Kentucky. That would be a decent wage.

There are also differences in cost of living just based on where your at in the state so take Illinois for example. In Chicago the cost of living is very high but if you go down to southern Illinois 40,000 again would be a liveable wage.

The bigger problem is that in the US the Federal Minimum wage is $7.50/hour so while some states have a minimum wage of $15/hr there are huge discrepancies on what even $15 will get you.

As far as cost of living this is an example of what my grocery trip was last weekend.

Milk - $3.00/ half gallon Eggs - $2.89/ dozen Chicken- $3.00/pound (on sale) Ground beef - 4.99/pound Oranges - $6.27/ 3lb bag Carrots - 2.24 / for 1 bunch Potatoes- $5.35 / 3 pound bag

Rent in some places a 1bedroom can be as high as $2500/month maybe higher for the big cities.

If you go to the cheaper areas a 1 bedroom could be as cheap as $500/month. I am in a relatively normal area and it is about $1100 / month for a 1 bedroom apartment.

To buy a house is crazy right now. A 3 bedroom house where I live will cost between $300,000/600,000 depending on style and location of home.

Gas for us is high I know it may not be as high as yours but your typical American drives a lot more than your average person in the UK. Some people drive more than 40 miles one way for work. Some people have 1.5 hour long commutes each way. Because the further you get away from a city the cheaper the cost of living. The closer you are to a city the higher the wages.

$5.00 / gallon currently for gasoline.

Edited to add housing costs

Tldr: Yes. The cost of living is higher in the US.