It's only an invitation for police harassment if you're breaking the law. And in your version, you would instead have been arrested / fined immediately regardless of anyone reporting you.
The bottom line for selective enforcement is that the police recognize that there is a priority structure in laws. They have limited resources and cannot enforce every law, everywhere, every time. While I would rather see this law unmade, the second best thing that can happen is exactly what is, which is the police only getting involved if an actual legitimate issue is raised.
EDIT: A second pertinent example is noise ordinance, which this is similar to as a "public nuisance" law. The law is not worded that it's OK as long as all your neighbors are OK with it. In your world, police would be walking around neighborhoods with a decibel meter and fining every non-compliant house, regardless of whether you cleared everything with your neighbors, or even if your neighbors are the ones making all the noise at your party!
I see this a closer to something like prostitution laws that are selectively enforced in many countries and lead to large scale police corruption/harassment.
Random rant: my limited experience of police treatment of homeless people in San Francisco leaves quite a lot to be desired. I've spent about one month in total there and I saw police hassling homeless people quite frequently. Anything that makes that easier is bad in my mind. Sure - poor people are an "irritation" by some definitions but they remain people even if their existence is inconvenient to some.
I agree with your principle whole-heartedly; I was just pointing out that I feel that police harassment is an orthogonal concern, and that selective enforcement is a Good Thing in the vast majority of cases -- ie, all the ones you never hear nor think about.
If they are going to harass you when you're not breaking the law, then the law itself has nothing to do with it. They could equally harass you for any number of things which no one would argue should be criminal. Making a statement about police harassment and abuse of power is fine, but the topic at hand has little to do with that.
I suppose my point is that, when a law is selectively enforced, minorities and the poor are the ones who tend to get "selected," which I do think is relevant to selectively enforced laws - they are often enforced in a discriminatory manner.
Edit: I clearly did not explain this with the post above, which upon re-reading makes little to no sense in context here.
The bottom line for selective enforcement is that the police recognize that there is a priority structure in laws. They have limited resources and cannot enforce every law, everywhere, every time. While I would rather see this law unmade, the second best thing that can happen is exactly what is, which is the police only getting involved if an actual legitimate issue is raised.
EDIT: A second pertinent example is noise ordinance, which this is similar to as a "public nuisance" law. The law is not worded that it's OK as long as all your neighbors are OK with it. In your world, police would be walking around neighborhoods with a decibel meter and fining every non-compliant house, regardless of whether you cleared everything with your neighbors, or even if your neighbors are the ones making all the noise at your party!