Actively telling all your hooker friends to stay home because the cops are out is not illegal. Nor is it illegal to say "oh hi there officer" before your hooker friend propositions a cop. That's basically what Uber did.
Not only will you find examples of things like courts finding liability if "a newspaper publishes the name of a witness to a crime, thus making it easier for the criminal to intimidate or kill the witness" (with no intent on the part of the newspaper) [18] or "a Web site or a newspaper article names a Web site that contains copyright-infringing material, or describes it in enough detail that readers could quickly find it using a search engine" [26], there are also examples more directly relevant to this situation. I think references [19, 37, 38, 39, 40] are most relevant.
[19]: "publish[ing] . . .the residence address or telephone number" of various law enforcement employees "with the intent to obstruct justice" is illegal in many states, including California.
[37] My reading of United States v. Lane, 514 F.2d 22 (9th Cir. 1975) is that advising people not to sell drugs to a person because you heard something interesting on a police scanner is aiding and abetting a conspiracy. The court said the defendant "could not seriously contend that he was discouraging, rather than aiding and abetting, the commission of the crime" in response to his assertion that "he actually advised against it".
[38]: My reading of United States v. Bucher, 375 F.3d 929 (9th Cir. 2004) is that it is walking down a trail to warn a person whom park rangers intend to arrest is interfering with both the rangers and their official duties (and thus illegal).
Seems more akin to developing a system to screen guests at your hotel - which you insist isn't an illegal brothel and is making good faith attempts to uphold the law - to ensure you're only earning "enhanced room service" commissions from people that aren't investigating whether they might be illegal.
Even if that isn't an offence in itself, it still looks like hard evidence against any claims they might make of intent to comply with the law in various other cases being brought against them.
Which could be obstruction.
If the app told them they were banned, it would be closer to your analogy. But, it shows fake cars circling about that never pick you up. It's actively deceiving law enforcement
first, and most important to this discussion, is that it is definitely deceptive especially when you are going to such extremes as documenting burner mobile phones and preventing their use on the pretense of hiding from regulators.
second, and less important for this discussion, but a business has he right to refuse service to any ONE person for whatever legal reason they choose (whether they specify hat reason or not is a different topic). this should not be confused with deniying service to a GROUP of people for whatever reason they want which is discrimination, and is illegal, whether outline in a TOS or not.
Uber built an infrastructure to be able to systematically detect and obstruct officers in all locations they are operating.
Comparing this with saying "hi officer" is a slight understatement.
While in that case, intent would be be very difficult to prove, it's rather obvious if you spend planning time and resources building a software tool with the express purpose to warn you of officers.
That's a valid distinction to make, however given how much development effort companies like Uber and VW invested in their tools, I think those are clear cases of active deferring.