Because the vast mass of people are lazy and/or ignorant, and the remaining people who are neither are either engineers or market drivers. Engineers keep the lights on and typically are not independently wealthy; market drivers reinvest the technology and science back into the market to create a captive market as services (non-ethical software).
Furthermore, a majority of the front-running FOSS projects of the last decade have been co-opted by FAGMANN companies or destroyed by entryism by Rob Pike-alikes with awful fucking ideas. A few neckbeards keep any sort of FREE AS IN FREEDOM web alive by self-hosting and writing good notes, but this is seriously less than 1% of people and it will never tap into the auto-amplifying feedback loops which market mechanisms work on.
Consider the number of people developing "open source software" on iBads/fagbooks working for tech firms, vs the number of people willing to demand FOSS software and actualize on it: the number of engineers willing to pay the actual price of freedom (lower convenience, lower interoperability, more time investment, actual money for hosting fees) is low and will always remain low.
One can do their part by refusing to buy into it, by instead choosing to self-host services, and to make our methods known, but it only really goes so far. Ethical software will remain esoteric knowledge (as will understanding of computers, oddly enough for the same reasons.)