Walmart did this with their wifi recently, you have to enter an email to get access. Of course it makes sense that mobile data doesn't really work inside a giant steel warehouse, 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.