Edward Snowden has some suggestions for how guest wifi should work:

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Instead of changing your phone to change your persona — divorcing your journalist phone from your personal phone — you can use the systems that are surrounding us all of the time to move between personas. If you want to call a cab, the cab doesn’t need to know about who you are or your payment details.
You should be able to buy a bottle of Internet like you buy a bottle of water. There is the technical capacity to tokenize and to commoditize access in a way that we can divorce it from identity in such a way that we stop creating these trails. We have been creating these activity records of everything we do as we go about our daily business as a byproduct of living life. This is a form of pollution; just as during the Industrial Revolution, when a person in Pittsburgh couldn’t see from one corner to another because there was so much soot in the air. We can make data start working for us rather than against us. We just simply need to change the way we look at it.
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   – Edward Snowden
     in http://www.popsci.com/edward-snowden-internet-is-broken