Benefits vs. risks (Score 1)

Regarding the chance of a cafe owner receiving a subpoena, it won't happen, because the cafe owners don't provide the service. Cafe owners pay a fee to an internet service provider. The ISP places a wireless router in the cafe. The cafe then either sells access, or allows free access. So, any subpoena will be served on the ISP.

Offering free wireless access can be either good or bad for a cafe, depending on the business climate. If the cafe enjoys good business, then it is probably better off charging for access. This is because wireless users tend to spend less over the time they sit in the cafe. If business in the cafe is slow, then offering free access is a way to bring in a little extra income, while also creating an appearance of popularity (an old trick in the restaurant business.)