Legislative cowardice to actually make the law reflect reality, I suppose. Funny how I can't just decide to relax my vigilance with regards to paying taxes.
Don't "enforce the hell out of the law" like a rookie cop with a hard on. Instead, realize that one of the most important jobs of a city is to strike the right balance to make the city an awesome place to live and work.
Laws don't always have to mean heavyhanded enforcement; sometimes they just provide the authority needed to deal with a potential problem in case it ever actually becomes a serious problem.
(Which smoking a cigarette in an outdoor park really, really isn't. I don't care to stand right next to smokers either, but in an outdoor park you really don't have to.)
Prohibition was essentially a social/cultural movement that was very bad law making possession and distribution of alcohol illegal because it had the potential to lead to things that were already illegal (public drunkeness, etc).
These public smoking bans in theory are crafted because secondhand smoke (be it from tobacco or another source) has the potential to cause cancer in people standing nearby in a public park.
Of course, neither prohibition nor smoking bans in public parks were ever really about preventing minor incidents of public drunkeness or absurdly low risks of cancer from secondhand smoke. They were obviously about abusing the law in order to discourage behaviour (drinking, smoking) that were previously a cultural norm but for which no actual justification exists for ending.
Really bugs me, but I'm obviously biased by preferences for minimalism in regulation and law.
I think it is good policing, though. Seattle has a pretty great police department, especially for a city so big.
Now, the cops deciding how and what laws to enforce doesn't always work out well, but as a practical matter that is part of what police departments have to do in every city, and Seattle's police seem to do it particularly well.
Unenforceable (or very difficult to enforce) taxes occur too. For example: http://en.wikipedia.org/wiki/Use_tax
You make this all sound like a terrible thing. Not punishing consensual "crime" is excellent, and refusing to enforce unjust laws is the opposite of cowardice.
That's what I mean by cowardice; on the part of lawmakers who don't want exercise the courage to make the law reflect reality and instead just do whatever is politically expedient.