As far as I know, that's illegal in the US to interfere with cell signals. A big box store like Target is a poor man's Faraday cage (he said, having 0 knowledg

As far as I know, that's illegal in the US to interfere with cell signals. A big box store like Target is a poor man's Faraday cage (he said, having 0 knowledge of physics) and offering free wifi is a small cost if it means people stay inside the store longer. Saying this isn't anti-competitive because customers can always ignore the free wifi misses the point: given the service issues in stores and the attractiveness of (usually) higher speed wifi, people are going to be drawn to it and no one is going to read the Terms & Conditions that say "Hey, we're going to try to prevent you from shopping for the lowest price!"