Yes. This is literally adopted directly from Neo Nazi playbooks. Nazis like using box trucks to transport mass groups of people for two reasons: they're everywhere, and they're opaque.

Once you load up in this, nobody outside can tell how many of you there are, what you're carrying or kitted for, and they can't ID you from the outside. When you leave, it's pretty easy to blend away into traffic, or dump the truck out in some residential neighborhood and scatter away without anyone knowing how many people were in the truck to begin with. You also have no way of knowing what else they're carrying in the back - weapons? People? Explosives?

The other reason Nazis like using these is it now immediately sets you on edge if you see a moving truck anywhere near a demonstration, or parade, or whatever. The fear is the point - we might not be THAT truck, but we might be the next, or the one after that, etc.