I've looked over a lot of discussions and seen how folks use wi-fi, but I have not seen an answer to what prevents someone from never paying for internet access and just using free wi-fi spots? Could one still browse the web, just in a "read-only"mode?
Q. What prevents someone from never using paid access and resorting to only free access?
A. Nothing prevents you from using choosing to exclusively use free access point over paid for ones. However if there are no free ones, then you have to make the choice of paying for access or going without any access.
Q. Is there a "read-only" mode?
A. There is no such thing as a "read-only" mode. You still have to "write" your page requests as an upload to view different web pages.
I can think of one exception where you connect and a splash page is delivered to you automatically without you making a request to read the page. A newspaper company could post their entire daily edition on one splash page and all you have to do is scroll down several under screen pages to read all the articles.