Some years ago (2004 to be precise), I took a train from Thessaloniki, Greece to Sofia, Bulgaria. Bulgaria was not yet part of the EU and did not have a lot of tourism then. That was part of what made it interesting to me. It also meant that the handful of tourists found one another and exchanged tips. And part of those tips had to do with "gypsies" and watching out for them.
The problem I had was that I had actually broken bread with a Roma king and I didn't necessarily share that bias. There is certainly a crime problem in that community, but the problem is not one of inherent criminality but of discrimination that often leaves crime as the only option. The long term solutions have to involve removing that discrimination and providing opportunities for education and advancement. At the same time, I would have been a fool to ignore the risk of being robbed by kids trying to distract me by waving newspapers in my face and other similar tricks.
The situation with police and African-Americans here is similar. We really don’t live in a world of equal opportunity and some of those conditions lead to higher rates of criminal behavior in some communities. It is not surprising that police, who see the seamier side of things, get conditioned to expecting violence and it may well be unreasonable for them to ignore the risks. Again, the long term solutions involve creating opportunities and eliminating discrimination. Unfortunately, there are no good or obvious short term solutions. We’re in a vicious cycle.