They don't currently, but they could.
Take brand x on the shelf. Sold for $5 at a profit of $1. They sell 10 per week. You buy 2 if those every week, on Wednesday at about 6pm. Why not make them $5.50 next Wednesday and see what happens. Normal price on other days as no pattern identified.
Then once that's successful, why not have beacons detecting your phone, or even the stores app feeding your location. Then they can update just for the hours you are there.
Oh, but you'll say you swore it said $5 when you picked it off the shelf. The worker will say they have to charge what's there now and what it scanned as. Your choice to purchase it or go look for something else.
They've already started all this crap with online purchasing. It's just moving it to retail.