I can't quote examples but serious crime cases have been dismissed for minor technicalities. You only have to look at drink driving cases.
Back on topic. If a clever enough person can expose a defect in the law fair play to them. I once lost a case because someone was smart enough to point out that if a double yellow line is broken at all it invalidates the whole section. Lesson learned and defect was fixed the next week.
But you said that people have gotten away with murder for smaller technicalities than the equivalent of disputing a parking fine penalty on the basis of the shape of the parking token. I guess you just made this up so?