Jonathan Cohn explains it well. The back story is that the Big 3 decided decades agp that paying lifetime health care themselves was a better idea than supporting public health insurance for everyone. They were very, very wrong. Now, when new plants are built in the US by foreign companies, they pay their workers a competitive wage, but they aren't weighed down by the cost of providing health care for a couple generations of retirees. This was sort of fixed in last year's UAW contracts, but apparently too late.