I think the reality is that there are both arrogant and non-arrogant doctors, just as there are good and bad in any profession. However, most of us have interaction with doctors at various stages in our lives, and so there is a shared experience that is talked about in a way that doesn't apply to less society-facing careers, such as computer programmers for example.
However, I think there is a tendency for high-powered/high-paid careers to be guilty of having an overall culture of arrogance, which isn't to say that individuals are, just that the career culture encourages it. It's a well-studied and documented sociological trend and is due to quite complicated reasons. Just two of those many factors are quite revealing:
To start with, anyone involved in a career where decision making has far-reaching consequences cannot survive without a high level of confidence in their opinions. Be that doctors, nurses, magistrates, police officers, social workers (all roles that have been accused of arrogance). If you don't have confidence, you won't survive for very long as indecision is perceived as weakness and leads to challenge, unpredictable results, stress and ultimately sickness, absence and people leaving the career.
Secondly, during training and the early years in these careers, you work through your reasoning for the decisions you make - quite often out loud in the interests of transparency and accountability. This has the nice side effect of making those affected by your decisions feel involved and less talked down to. As time passes and you become more senior, there are higher expectations on you to deal with more people in a more timely fashion. The result is that social niceties disappear. The decisions which once took 10 minutes to rationalise out loud and 'translate' to the individual, are made in a split second and are so familiar to the decision maker that they have forgotten how alien it may seem to the recipient (much like when you say something as part of a conversation with someone, then have a train of thought and say something which to you makes complete sense but to the other person is a complete non-sequitur leaving them thinking WTF?).