is it difficult to understand why there is so little trust in officers who are unable to subdue one man, armed with a kitchen knife, when the officers are armed with tasers and firearms?
A large part of the problem is that the police are over-armed.
To a man with a hammer, every problem looks like a nail.
Police are so completely dependent on their guns that they don't even consider a more proportionate response, and that's reflected in their utter failure to do simple defensive tactics like moving away from a person who is wielding a knife.
If they weren't routinely armed, they would, and could, apprehend knife wielding suspects without killing them. This happens routinely in places like the UK, where firearms aren't routinely carried by most police officers.
Officers are rarely injured in such confrontations, because they're trained and provided with appropriate equipment for the use of non-lethal force.