An ebook is still a physical good in a sense. The data (or some portion of it) rests on a medium in your possesion (even if only temporarily). As we all know, there are significant costs involved in creating, advertising, distributing, maintaining said digital good. The costs and subsidies (e.g. open source software, government research, corsortiums) are just distributed in a vastly different way, so much so that to some it may seem to be a free lunch (despite being far from it).