I've actually been looking into detail about this defence "de minimis non curat lex". I could see how it could be used for a number of parking or traffic offences.
Unfortunately, there's not much case law on it because it's one of the more complex common law defences and it's not used very often. But I would say that it's quite simple to understand and it could be used a lot more often, especially for parking or traffic offences.
Here would be a general argument to be used in court: "The purpose of the de minimis rule is to avoid the burdening of the courts with minimal complaints which would result in wasted costs, resources and time. It is further to avoid the situation where more serious crimes and claims take even longer to be dealt with due to these trivial issues taking up the courts time. This will result in the criminal justice system and the court system in general being brought into disrepute for not being able to deal with serious matters efficiently. The defence of de minimis does not mean that the act is justified; it remains unlawful, but on account of its triviality it goes unpunished. Generally, the justifications for a de minimis excuse are that: (1) it reserves the application of the law to serious misconduct; (2) it protects an accused from the stigma of a conviction and from the imposition of severe penalties for relatively trivial conduct; and (3) it saves courts from being swamped by an enormous number of trivial cases."
In general, a lot of parking and traffic offences would fit this criteria. And since "de minimis non curat lex" is a common law defence, it applies to cases under the Provincial Offences Act:
"80. Every rule and principle of the common law that renders any circumstance a justification or excuse for an act or a defence to a charge continues in force and applies in respect of offences..."
This defence could be used, for example, someone is charged with assault for bumping into them on a busy street; or someone is charged with possession of illegal drugs with an insignificant amount like 1 gram; or someone gets a speeding ticket for 1km/h over the speed limit; or someone gets a parking ticket at 9:01 when they paid up to 9:00, etc. etc.
I have not yet tested this defence out in court for parking or traffic offences, but I definitely intend on bringing it up in future cases. I don't know how well it would stick with a justice, though.