For years, conversations about the trillions in household spending that flow through everyday purchases have included what is often called the "pink tax." That's been shorthand for the idea that similar products can cost more when marketed to women: think personal care items (like a pink vs. blue razor). But historically, those differences have not always been easy for consumers to see or compare in real time. They were typically identified through comparisons or broader studies after the fact. Now, as Mother’s Day spending is projected to reach $38 billion this year, a different pricing system is changing how those disparities can appear. From just $107.88 $24.99 for Kiplinger Personal Finance Become a smarter, better informed investor. Subscribe from just $107.88 $24.99, plus get up to 4 Special Issues CLICK FOR FREE ISSUE Sign up for Kiplinger’s Free Newsletters Profit and prosper with the best of expert advice on investing, taxes, retirement, personal finance and more - straight to your e-mail.…