Saying mining is not a market because if it becomes dominated by a tiny number of players fees might go up seems backwards - surely higher prices due to lack of competition is exactly how you'd expect a market to behave?
Surely mining does not suffer from lack of competition. Its rather how pools shift power from consumer to producer. much economic research is spent on studying monopols, oligopols, polypols (1, few, many). oligopols often exist in resource markets like oil and electricity, because of scaling effects. its not that surprising we see the same in bitcoin. a miners tax is probably not a bad idea to redirect excess profits.