Except that the marginal cost of the Internet service is nearly zero. In this case, the guy who owns the business probably uses it to place orders or for other business uses, but when the place is crowded, he'll be handling orders as well as his staff. So basically he's letting his customers use excess capacity. If it attracts more people, those indivuals will tell their friends, helping to build up a customer base.
I used it this morning and during a discussion with a friend I met there, I ended up emailing a URL (literally to the person sitting right across the table from me) to save having to write down the link from a web site.