Well, can culture be specific? Think of it this way - when Solskjær came, one of the first things he did was go talk to the desk lady who’d worked there for ages. This was in stark contrast to the way Moyes, Van Gaal and particularily Mourinho treated the members of the club that weren’t eligible for the next league game. Many people at the club had been there long enough to know how Sir Alex always treated her with the same level of respect and interest as he did star players and board members. Small things like these add up, and help knit bonds that will be important when the going gets tough. Ferguson himself did almost the same, when he came to the club he studied everything about United history, and everything about Sir Matt Busby. He knew the deeper knowledge was part of the bigger picture both of what dreams may thrive in the corridors of such an institution, and what practices may need to be developped - at many levels.
Sir Alex was close to the sack several times during the first six years. One may ask if the people who didn’t sack him really where so prescient about how his methods would inevitably turn things around, or wether how he respected the culture of both the club and the people working at it buy him time, acceptance and support at the club, making him survive where anyone else would’ve been axed.
As for Solskjær, there have been several rounds when his head has been called for. People assume he is tacticly weak, inexperienced as an elite coach, too soft, etc. And entertain this: If he is indeed behind so many in coaching methods and tactics - how has he managed to keep the job for three years, to get pros and stadium fans to get behind him and stay behind him, to get capitalist speculants to inveat money for good players for him, and to steadily increase the points tallies, heighten the league placings and deepen the cup runs - is he a much better manager than credited, or does the fact he knows and respects culture embedded in the club (among board members, functionaries, players and coaches, fans, community people and even a lot of expert commentators, old buddies so to speak) actually help him in getting the job done, not having to work against people, moods, traditions, habits, not having to reimplement a thousand things every week anew, and having people fight for him after each set back, despite doubt, despite critics in the press and SoMe, despite 20 players in the squad who play less than they think they deserve.
There is a lot of culture living in the people connected to Man United today, and the stories of Sir Matt, The Babes, working class railwaymen, Georgie Best and Sir Alex form helix strings within that culture, making it easier for anyone who can sail with it and harder for anyone aiming to go against it.