The article you linked to, regarding Target, is exactly what your corner store cashier is doing. There is literally no difference.
You are conflating two different things - stores retargeting existing customers and recommending products they think are relevant vs. ad networks like Google that track you across channels so that they may serve the most relevant ads to you based on your interests.
Neither are bad, and both are necessary. Tampon advertisements, for example, have no effect on men - men would find it annoying to see tampon adverts constantly because they are not part of the market.
Why would an advertiser want to advertise to people who will never make a purchase or care about their products? If you're a hiker though, it's really fitting to get advertisements for hiking gear and equipment.
