Unfortunately comparing European and US salaries is comparing apples to oranges.
Not only there's vacation as other people mention, but most importantly and often ignored : tax rates and retirement.
In those 55k, you also probably have a bigger tax bill, so it would be more fair to compare money that ends up in your pocket.
Retirement: you probably have a national system, with a formula that tells: if you worked X years at salary Y, your retirement income will be Z.
You might also have extra retirement plans if you want to save more.
In the US, retirement pensions is not a thing (except maybe public servants etc?), So you're responsible of saving by yourself. The employer will sometime help (like for every dollar you put in your retirement plan, they'd match 50 cents, up to ~20k per year), and that money you put in the retirement plan is tax free, but the point is that it's money you theoritically should not access until retirement.
With those 2 factors, the money you actually get to use is different, and then the cost of life is different: raising kids in the US until college, would be a different price than a kid in the Netherlands until the end of university.
Are we looking at the same Netherlands? A quick search tells me California's highest bracket is 13%. In NL you're lucky to get ~25% effective rate as a knowledge migrant, going steeply up to 52%.
You are right but you have to also consider US working hours. Apparently it's not unusual to work 60 hours a week while here in Europe we have ~40 hours working weeks. If I have to choose I would definately stay on my UK salary that is about half what this calculator is showing for my experience and keep 40hr working week.
Not only there's vacation as other people mention, but most importantly and often ignored : tax rates and retirement.
In those 55k, you also probably have a bigger tax bill, so it would be more fair to compare money that ends up in your pocket.
Retirement: you probably have a national system, with a formula that tells: if you worked X years at salary Y, your retirement income will be Z. You might also have extra retirement plans if you want to save more. In the US, retirement pensions is not a thing (except maybe public servants etc?), So you're responsible of saving by yourself. The employer will sometime help (like for every dollar you put in your retirement plan, they'd match 50 cents, up to ~20k per year), and that money you put in the retirement plan is tax free, but the point is that it's money you theoritically should not access until retirement.
With those 2 factors, the money you actually get to use is different, and then the cost of life is different: raising kids in the US until college, would be a different price than a kid in the Netherlands until the end of university.