a bit late to the discussion but I think the scene with the paramilitary police force also has a really important meta role in forcing the reader to critique policing. It's an extremely common trope in manga to have the protagonist catch a criminal while they run away from the scene of the crime, only to hand them off to a clean, sanitized police force and never see or think about them again. Once the police leave both the character and reader are free to forget and stop caring about what happens next.
Here Benika does just that, but instead of the "officers" taking the guy off the page forever, Benika is brought to the area where the criminals are held, and seeing the cages, people sitting with bags over their heads, and the pile of skulls, those cleanly smiling vigalantes are no longer quite so sanitized, especially when she finds out what they actually do to a lot of the people here. The fire she's invited to warm herself by is quite literally a pyre for burning the bodies of criminals.
Regardless of if you think the vigilantes are in the right or not, the way this entire narrative was framed, both for Benika and the readers by extension, does a great job at forcing us to actually confront the realities of policing, and putting task of enforcing rule of law into a handful of armed people.