Whether you are a Canadian citizen or not, you can get a hefty fine for illegal camping in the parks.
And if you are not Canadian, you can be barred from future entry if the offence shows on your record.

More importantly, if the single person "roadside" camping is multiplied hundreds of times, every night -
it places an undue stress on an already heavily used and fragile environment.
Human urine has lots of salt - something often rare in the natural ecosystem.
Salt-starved wildlife will be attracted to the roadside and be more likely to be hit by cars.
Among many other issues ....

Dispersed camping is great on BLM land in the middle of Nevada.
It isn't in national parks.