alt Hacker NewsIt's illegal in a few places in the US, but not everywhere. It's definitely not illegal to put in a few kW of amplifiers and a few square feet of speakers, and often not even a problem to turn them all the way up and stop whole areas from hearing anything.
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.