I wish everyone used DDG for the sake of privacy, but I cannot. It just doesn't give me answers that I am expecting. It reads my mind less than Google and that's a problem.
Furthermore: if a retailer can use my location data to predict demand, they can optimize their logistics and save fuel.
Do you think those cost-savings will be passed down onto you?
Most of retail is notoriously competitive. The savings are likely to be passed down at some point. In general retail if you can persistently charge 5% less than the competition across the board, you're the next Walmart.