That’s because “bad cops” are criminals operating under to color of law and carrying guns and badges.
It's so much easier for those bad cops to do that than to actually risk their lives and do real work going after truly dangerous, heinous criminals.
THAT is why bad cops are worse than bad criminals -- they cultivate weeds in their backyard so they can pull them (if they don't shoot or beat them to death first).
GOOD cops understand which folks are truly dangerous and bad, and which (the vast majority) are just law-breaking rebels. A criminal is very different from a rebel. A lot of good cops are rebels themselves. Virtually ALL bad cops are self-absorbed bullies who abuse their power in order to cultivate criminals they can arrest.