The way Fusion Tables are set up can be pretty confusing. In order to embed your table somewhere, you have to make the Google Docs data behind it public & searchable. http://support.google.com/fusiontables/answer/171221?hl=en

My guess is a lot of people are creating data visualizations for their own site/business and making the sets public without thinking of them being indexed and searchable. As I said, the documentation on this within Fusion Tables is pretty awful.