It just feels so petty. Not a single person reading "less cops" was confused by its meaning. I get fighting against misuse of your/you're, its/it's, etc. because they can make things harder to read. Fewer and less, though, have the exact same underlying meaning (a reduction).
I'm something of a grammar Nazi, but just like I support letting "whom" die, "less" and "fewer" might as well just be interchangeable. There's no loss of language utility in doing so, unlike "literally"'s tragic demise.
That is how language works. It starts off small, then it catches on over time, and after a long time has passed, it either gets filtered out, or it becomes commonly used. The case for literally being used, for reasons other than its original one, started a couple hundred years ago. Today it is super commonly used that way, as it didn't get abandoned. You are mad at the nature of the beast.
This one isn't even real. "Fewer" can only refer to countable things, but "less" can refer to both countable and uncountable things, and has been used that way for hundreds of years. It has never been wrong to say "less."
I’m a grammar loving curmudgeon. Even I check myself more often than not after I realized the kind of classist tones that come through when arguing against lexicon.
I actually kind of disagree in this context. Less is sharper and more readable while conveying the same meaning. The grammar books might say it’s technically incorrect, but I think it was the right word to use here.
Essentially, fewer is normally used for discrete numbers of things (e.g. "fewer apples", "fewer boats", or "fewer cops") while less is used for amounts (e.g. "less water", "less sand", or "less money").
As noted in the above link, there are exceptions. However, the exceptions listed are all with "than" or "or" added. Specifically, it's pointing put that while "fewer items" is correct, "3 items or less" is also considered correct.
In the case of the sign, it is referring to the specific number of officers in the city, so it should use "fewer". Does it matter? No, not really. Why did I bother saying anything? I got a chance to rep grammar and quote Stannis Baratheon at the same time.