Normal bricks block sound.

Acoustic bricks absorb sound, turning it into other energy. Commercial acoustic bricks example - https://www.randerstegl.com/en/wall-bricks/other-types-of-br...

So there is a Commons issue, why would I buy far more expense acoustic bricks when I can just reflect the sound, ie back at the cars.

Additionally bricks collecting stagnate water is very bad, and in a urban environment collecting dust and insects is bad.

Off topic but tress absorb a fair amount of noise and like Telsa's appreciate in value over time.