I don't think this should be annoying you too much. Sure it would have corrected your behavior, but it wouldn't have emphasized to everybody who hears about your experience just how important it is to research every location they want to shoot. It would also contribute to the sense that one can just go fly in restricted areas and pretend they didn't realize that what they were doing was illegal in the unlikely event that they get caught.
In Canada, you can't fly in National Parks, but you can fly in some province's (but not mine's) Provincial Parks. Like the rules in your National Parks, the rules in Canada and my province provide for the loophole that a flight could be initiated outside the park and operations conducted inside, as long as no takeoffs/landings occur inside the park. I believe your rules would preclude you from walking into the park after takeoff, while mine do not. I knew that from my initial research before I even purchased my Phantom.
Note that if you're flying under the "takeoff outside and fly in" loophole, you should be prepared to be ticketed. The officers likely won't be as nice as these ones were either, because they might see you as being difficult when you start quoting the letter of the law. I'd have a printed copy of the relevant law if I were you, and be prepared to fight your case in court if you're planning to capitalize on any such loopholes.
After reading your OP, I decided to do some additional research in case any other areas I fly or plan to fly is restricted. What I didn't know is that there's a bylaw against me flying in city parks (whether or not that flight is initiated outside). I'm glad I wasn't caught the few times I unknowingly violated this, as any sort of record of bad flight practices could possibly impact future applications of mine for a Special Flight Operations Certificate (SFOC), which is a requirement in Canada for any commercial operations. I also found that I was mistaken on the areas I couldn't fly in my area without applying for a SFOC due to small helipads, such as those attached to hospitals.
For any other Canadians, check out:
UAV Site Selection Tool - National Research Council Canada
But note that it's incomplete since provincial and municipal rules don't appear to be taken into account.
Thanks for posting your experience, as I was just about to fly in a city park with a nice downtown view that was technically also restricted airspace due to a nearby helipad, and the fact that our city's international airport has a specially extended restriction zone.