Generic Cop Badges

Badges in many cop shows are generic, with just the words "Police" and the car decals are the same. Police forces may well be fictional, even if they are in a real place.

Related is a British TV trope in which London bobbies' epaulette numbers will have a letter "O" in their two letter code—e.g. SO 171 (Reg Hollis in The Bill). There are no divisions with "O" in their two letter code in the Real Life Metropolitan Police.

Examples of Generic Cop Badges include:

Film

Transformers (2007 Movie): In a clever usage and in keeping with series tradition, the department emblem on Barricade's police car form is actually a Decepticon crest. Also, the motto on his side reads "To punish and enslave".
In Blue Thunder, the squad cars have a huge "Metropolitan Police" decal on the front doors.
In SWAT, the cops wear the generic "Metropolitan Police" badge.

Live Action TV

The British Cop Show Mersey Beat, despite its being set near Liverpool, is under an area called "North West County Police".
Starsky and Hutch, anyone?
The Shield, after its first episode, not only uses fake badges, but places them on the wrong side of the uniform, at the request of the LAPD (due to the portrayal of the cops as...less than upstanding).
- In one of the episodes, Shane is mugged in Mexico and loses his badge. For the next several episodes until he is discovered, he uses a counterfeit one. A fake of a fake.
Exceptions: Joe Friday's badge in Dragnet is a real LAPD badge, and its badge number (714) is officially assigned to the fictional detective. The Bill is allowed to use real Met Police decals and badges.
Life On Mars tried to avert this - then realised too late that Greater Manchester Police are not the Metropolitan Police. As a result, Sam Tyler's badge is digitally genericised on the DVD release.
The crew of Mystery Science Theater 3000 call attention to this when the "Desert Patrol" shows up in Eegah.
Lampshaded in Police Squad!; marked police cruisers are seen only in the background; they are highly official-looking black-and-white full-size sedans, very authentic except that the door decals read "POLICE CAR".
When MythBusters tested a story of a police badge stopping a bullet, they got test badges from the company that makes the real thing, but genericised.
This trope is how the title character of Furuhata Ninzaburou catches on that the supposed police officer he is talking to is an imposter—the other man doesn't notice that the badge Furuhata shows him is a prop (long story).