That's why you should not be using averages for comparisons like this.

The low end in Sweden is based on the local minimum wage and the vacation days are mandated by law. In the US IKEA uses the room afforded by the law there to pay their workers what they can get away with.

Clearly these are not 'average' Americans or Swedes we're talking about, we are looking at the low end of the curve.

Cost of living for those American workers is likely not all that much different from their Swedish counterparts.