Not entirely sure if this is possible but I’m increasingly suspicious that they started jamming outside networks within their warehouse. Of course it makes sense that mobile data doesn’t really work inside a giant steel warehouse, so perhaps it’s just confirmation bias, but I can’t seem to recall not having any mobile data signal at all until my last walmart visit.
I used to keep to myself and look up the location of the item I was looking for online. If they want me to bother a floor person for it though, doing that is highly preferable to giving walmart my email to sell along with any information they can extrapolate from my usage of their network.