Your experience is not universal. Out of myself and many young friends, there are few bad dealings with Police and mostly positive. Including people convicted and sentenced.
Fair enough. My experiences have left me very cop-shy.
In 2007 I had removers sho, rather than taking my belongings from A to B, took them from A to an auction house. The police started with a stance of "it's a civil matter" and ended with a stance of "we will prosecute you for wasting police time".
In 2002 my girlfriend at the time was receiving unsettling, perverse text messages from an unknown number. When I responded in an equally threatening tone, I had a call the next morning from East Kolbride police for sending a threatening communication to a police officer.
In 1996, I was arrested for being outside in the snow, aged 13. I was kept in a holding cell and denied food, water, or the means to contact my parents.
I have a very, very low opinion of the efficacy of the current application of the rule of law.