Much the same can be said about police forces in the United States, and for the same reasons.

Reform is difficult because police recruits are drawn from society at large, from a pool of people who are likely to be racist, sexist, and/or homophobic.

But as certain people I know in law enforcement tell me, there's a little more to it than that. People who are drawn to careers in law enforcement tend to come from conservative elements of society. So they are even more likely to be racist, sexist, homophobic, etc.

So even in quite liberal areas (I'm thinking of places like San Francisco or Seattle) where the general population is less likely to be problematic, local cops tend to reflect a much more conservative (and therefore much more toxic) minority.

How to work against that problem is something I don't have an answer to.