Those loudspeakers on wheels at volume are illegal in many places -what’s not happening is police caring enough to make arrests. Maybe other jurisdictions will take a cue from Las Vegas and begin enforcing laws to protect normal people from teenagers and adult idiots who still think they’re teenagers taking over streets.
Arrests seem like overkill. Ask them to stop, issue a fine, whatever. Sure I get you're asking for any enforcement at all. But hyperbole has a polarizing effect on discourse we should try to avoid, IMHO.