article does not present the exact same argument as Krugman, but it does suggest that the results of empirical studies can uncover solutions that can be applied to the market by force, thus enhancing transactions for the betterment of humanity. This is where I disagree with Krugman, the aritcle, and you.
Of course minimum wage laws have differing imapcts to differnet wage levels. A minimum wage increase set to 1% the median wage would impact significantly less transactions than one set to 5% the median wage. This is not the argument. This is irrelevant. Minimum wage laws outlaw employment set at certain price levels. Not only is this immoral, but it distorts the market and introduces unpredictable untintended consequences. The empiracal studies you reference cannot factor in the entire market response created by fixing prices, because the effects are so vast and not predicable. How do these empirical studies plan on compiling the data of those wage earners forced to accept wages "under the table"? How are their wages impacted? You cannot know, because it's impossible to find the data. How do these empirical studies compile data based on rise in prices created by the cost of labor rising due to minimum wage laws?
You cannot apply empirical studies to economic transactions. Price fixing is price fixing. It doesn't matter if it is in wages, fuel, or money.