NC as I have spoken to people about this IRL.
I didn't know until very recently that our home broadband hub in our hallway is also being used as a public wi-fi hotspot by other passing BT/EE customers - did you?!
If, like me, you didn't know that and have noticed strangers hanging about outside your home with their phones then this may be the reason. I had assumed all the hotspots were in businesses or via masts, so I was a bit perturbed when I found out by accident that our hub was a hotspot. I would have liked to have been asked first. You can opt out, but only if you don't want to use other BT/EE hotspots yourself.
YABU: Yes, I knew my hub was also a public wi-fi hotspot and I don't mind
YANBU: No, I didn't know and I don't like the idea or I should at least have been asked to opt in