Interesting. I've never seen that in the Nordic countries or the US. Typically either the wifi is just open entirely, or there's a WPA password written on a little card by the cash register. Helsinki even has open wifi across the whole downtown, and in Denmark all the Baresso locations have open wifi (no login or password). Does the UK have laws requiring the hotspot providers to collect that information, or are they doing it of their own accord for marketing or abuse-reduction reasons?
Also I haven't seen the terms, but I'm wondering if Facebook give out direct personal information. Assuming they don't, would you rather be seen as John Smith of 14 Main Street, DOB 1990-08-23 or 18 - 24 male who likes football?