They also don't help much any more. Not with cameras that do color, infrared, 4K or 8K video, high dynamic range, and vehicle make and model recognition.[1][2]
In the first video, note the checkbox in the analysis program for displaying vehicles with "strange plates" which were in range for reading but not read. Trying to obscure a plate draws automated attention.
Big Brother has AI, too.
Flock will use things like bumper stickers, tow hitches, roof racks, body panel color differences, wheels/rims, and window tints to add to vehicle identification metadata".