Pretending to be subject to a law however in practice never prosecuting opens the door to inconsistent (aka selective) enforcement. How is this not the worst of both worlds?
What a weird gotcha....
You've got it backwards mate, a lack of enforcement isn't an agreement or resolution or much of anything reliable or solid or sound. This vacuum of enforcement actually ENABLES selective enforcement because a lack of enforcement isn't an official stance but technically at odds with the written law: It's an implicit status quo that could be changed any time and when it does, you could become retroactively liable for behavior that was acceptable under the prior status quo. That is precisely the conditions of selective enforcement: the choice of the enforcer. Under these inconsistent regulatory modalities you may insidiously lose valuable rights like: No Bill of Attainder or ex post facto Law shall be passed.
Laws and their enforcement will always have some nonzero amount of selectivity by the localized nature of the universe but good legislation confronts these challenges proactively and tries to make prosecutorial discretion closer to the question: What should the Punishment be? Rather than: Is this behavior Punishable?
>> an implicit status quo that could be changed any time
> So is a history of enforcement!
Are you really saying that history can be changed at any time?
While there will always be jurisprudence that attempts to advance precedent, a history of consistent enforcement cannot, in fact, be changed. People will always have vulnerability to novel interpretations and surprising re-interpretations of the law, but laws which sit on the books IGNORED can easily lead to essentially undefined behavior which I have no doubt you can understand the potential pernicious nature of...
Not true [1]. (Enforcement leaves much to be desired.)
[1] https://en.m.wikipedia.org/wiki/STOCK_Act