Probably because most people don’t know the difference? Or the volume of water makes it too expensive and cumbersome?I don't know why pie joints and bakeries don't (maybe they do) buy reverse osmosis or even deionized water filters (almost pure h20 ) and tout it. And if they want specific minerals in their water it's soooo easy to do like breweries do with their water, sometimes changing from batch to batch depending on the style of beer they're brewing.