This may be anecdotal, and most certainly personal, but I watched someone falsely accuse me of battery after they themselves had actually shoved me to the ground, and I was arrested for battery. Cuffs, ride, the whole deal. My repeated explanations of what actually happened didn't even make it into the police report.
While false accusations are certainly less common, a blanket "believe the accuser" policy without requiring any evidence enables false accusations, and there is little that can be done to fight them.
I'm lucky because I have enough money to make my way through the legal system, but no, the system failed utterly.