If the roads were designed with traffic calming in mind you wouldn’t need stealth vehicles to enforce the law. The law would be intuitive and you would feel unsafe breaking it regardless of police presence, meaning there would be a lot more things on your mind than looking out for obvious police vehicles. A clearly marked vehicle would do the job.
We still need both. Even the safest design of a road could still let someone drive recklessly and dangerously.
If the roads were designed with traffic calming in mind you wouldn’t need stealth vehicles to enforce the law. The law would be intuitive and you would feel unsafe breaking it regardless of police presence, meaning there would be a lot more things on your mind than looking out for obvious police vehicles. A clearly marked vehicle would do the job.
People feel unsafe doing double the limit on a highway. The unsafe feeling is thrilling for some.
That just proves my point that they aren’t on the lookout for cops and the stealth vehicles aren’t solving any real problem.