I find it hilarious that you're arguing Wal-Mart pays lower wages in California because it receives a subsidy while the same company pays higher wages in Canada because, well, it receives a subsidy. Presumably, Wal-Mart got religion in Canada and decided it can't hoodwink the competition, eh? You haven't explained why there's an uneven playing field in California and other companies are stuck paying higher wages than Wal-Mart. Maybe you have competition hampered by collective bargaining agreements in mind? I would say those workers can bargain for higher wages, but it seems a bit disingenuous for them to then claim they're playing on an uneven playing field when they were the ones with the shovels.
Anyway, let's look at another example. In Texas, Medicaid eligibility is pretty difficult compared to some other states. For example, a pregnant mom in Texas can't earn more than 185% of the federal poverty level in order to receive benefits, while under California's Medi-Cal program she can earn up to 250% of the FPL. So under the "Medicaid Is a Subsidy" theory, to the degree that the "subsidy" is less than other states like California's, it should result in higher wages. And yet we see that Wal-Mart pays its Texas associates less, on average, than those in the rest of the country.
I realize that other factors may be at play to explain the difference between wages among the various jurisdictions, but the argument that a Medicaid "subsidy" results in lower wages seems tenuous and anyone making such a claim should put up some stats to prove it. In the meantime, this has union lobbying in Sacramento written all over it.
Walmart Stores Salaries in Texas | Glassdoor
Walmart Stores Salaries | Glassdoor