Why is Moyes completely expected to coach and run the club? That may have been the way Fergie did it, although even he began delegating more as time went on, but Moyes was given free reign to do as he desired. He could've hired four or five first team coaches if he wanted. Someone to take training, someone to do tactical drills, a defensive coach, an attacking coach, he had absolute carte blanche to build the regime he wanted. If the job is too much for him that's his fault. He chose to do it this way.
Everton have changed manager once in 11 years, they seem to be doing totally fine. I don't know how Martinez is doing things at Everton, in terms of how he arranges off field duties, but on the pitch the difference is clear. Players like Barkley and Pienaar have come out and said he's better than Moyes, more tactical and gives them more confidence. Again, Martinez is being judged mostly based on using someone else's players. He's made a few clever moves in the market, yes. But then Moyes has had two transfer windows already and hasn't shown that nous. Surely rather than pointing to the importance of Martinez's loans we should be asking why Moyes' only midfield signing is Fellaini, a player who controls the ball better at chest height than foot height.
Moyes has failed to put together any sort of coherent tactical plan besides get to the byline and cross. Moyes' defensive set up, especially at set pieces is useless and reeks off fear (nobody outside our box). Most of the players Moyes is working with have not known Fergie all their lives only Giggs, Clev, Fletch, Welbeck, Evans have been around that long. Most have been at most for half a dozen years, regularly go off and play well for their national sides, and come back and play rubbish for Moyes. So what does that tell you...?
Again, you're judging him different to every other manager on earth. Nobody else gets this kind of free pass for failure.