I have been pulled over and ticketed by unmarked. Just cause was the air freshener on my mirror "blocking my view" and traveling into a drug affiliated neighborhood (may I remind you I live there and travel it every day). Ticket was for failure to make a complete 3 second stop at the stop sign.
Indeed unmarked can and do give traffic violations. Took one to court before, added another 35$ fee onto it for court fees.
Assholes gonna be assholes. Some just want that easy "quota" (that thy cant write down or talk about as it's illegal). Job security.
This sir, is what we call corruption.