This wasn't really my experience... I went to school for CS, which involved using a bunch of open and closed source tools of different kinds. I wasn't aware of the distinctions between different kinds of open source, some of which fell within the OSI definition and some of which did not, I just knew that closed source stuff where I couldn't read the source was more annoying when things went wrong. I remember the moment much later when I realized that there was this whole (weird, to me) turf war over the definition. It still seems to me that the most straightforward definition of "open source" is just any software for which the source code is available (such that it is open, like a book).