The profit margins of a company should have no relationship to what they pay their staff. Total compensation should have a direct relationship to the prevailing wage for job titles requireing similar skill sets, and NOT just Union jobs should be compared. Though I have nothing against collective bargaining, when the relationship between skills required to perform essential functions of a job, and pay, becomes skewed to the point of being outside what would be considered normal and appropriate for the geographic area, corrections MUST occur. The company has a right, and even an obligation to both itself and the community, to make corrections in it's compensation plan, if it is based on sound compensatory factors and marketplace analysis.
This chit ain't f'ing rocket science. Determining pay scales/ranges is not something difficult to accomplish. Paying someone an appropriate wage or salary within reasonably established ranges can and should be a fairly objective process. I have not seen a job description or typical duties and responsibilities for a beginning line worker at HD, but based on my knowledge of both the Trades and sound HRM policy/procedure, I'd bet my next paycheck that 40K a year job, plus an additional cost to the company of 10-15K for benefits, is REALLY good pay. If the workers at HD wanted to propose a reasonable incentive pay plan, based on measureable factors like quality vs. production vs. profit, etc, etc, paid out every quarter or so, THAT would be a reasonable proposition for pay above and beyond fair and equitable wages.