All of this is pretty standard police procedure in the US. Once they have a suspect or target, they tend to simply assume they are a criminal, and their goal from that point is to find a way to get them into jail. Field sobriety tests and drug-sniffing dogs are two of many, many police tools that are typically used not to determine the guilt or innocence of a suspect, but to provide justification for arresting someone. Then they seize cash as "possible drug money" and destroy people's property under the guise of searching it.
After an arrest, police will often ignore exonerating evidence or not bother trying to get it, for much the same reasons. And they have a whole arsenal of tactics for making life a pain in the ass for the accused while they fight to get rid of bogus charges.
And after all that, they make filing a complaint as difficult as possible, after which the complaint either disappears entirely or seemingly sits in a drawer for months to years before ending in a generic finding of no wrongdoing from the officer.
As far as the police are concerned, the system is working as intended. Politicians may disagree, but they're too scared to make serious changes, so it never changes.
After an arrest, police will often ignore exonerating evidence or not bother trying to get it, for much the same reasons. And they have a whole arsenal of tactics for making life a pain in the ass for the accused while they fight to get rid of bogus charges.
And after all that, they make filing a complaint as difficult as possible, after which the complaint either disappears entirely or seemingly sits in a drawer for months to years before ending in a generic finding of no wrongdoing from the officer.
As far as the police are concerned, the system is working as intended. Politicians may disagree, but they're too scared to make serious changes, so it never changes.