When you FOIA body cams that will often redact the faces of other individuals.

Likewise I would expect that the license plates read be redacted. It makes sense to protect it since you are exposing members of the public, not the government.

Once you redact license plate numbers, what is left of substance in the FOIA request?

Generally they don’t redact that. They may redact private details not publicly visible (like someone stating a phone number) but if it’s public visible it’s generally not redacted.