Why cars are built in Ontario

This Newsweek story says why more cars are built in Ontario than in Michigan:

An American worker costs them more than $6,500 in health care per year. In Canada, which has a government-funded and -run health-care system, the cost to the employer per worker is just $800.

This ignores the fact that workers in Ontario pay insanely high taxes and that the auto companies negotiated themselves into this blackhole with the unions, just like they did with their pension issues.