Uvalde was a communication cluster fuck, not so much cop cowardice. It's fucking painful to watch, but here's the definitive documentary on what went down that day.

https://www.pbs.org/wgbh/frontline/documentary/inside-the-uvalde-response/

CAVEAT: You may scream and cry, I did, but that day was probably not how most think it went down. It wasn't so much scared cops. It was cops utterly paralyzed by a broken chain of authority and broken command and control infrastructure. I'll never watch it again.