Traffic tickets are "absolute liability"
Charges that are absolute liability basically mean if you did it, you're guilty... so you cannot dispute the charge on service (they gave the ticket to the wrong guy) the accuser must keep sight of the accused.
If the ticket is served at a later date, the officer has to testify that the person they saw do the offense is the person they served the ticket to (that's why they ask you to sign the ticket, that eliminates the defense of service). An absolute liability charge does not NEED mens rea (mens rea is a legal concept, that roughly means "guilty mind". You had to know you were doing wrong to be guilty).
... I am explaining this badly... traffic tickets are absolute liability, so the cop can't lose sight of the accused as per Canada Evidence Act, and you can dispute a charge on service.
No so with criminal charges (dangerous, impaired, crim neg, murder) where service means nothing to the charge. Mens rea MUST be proven on a criminal charge.
It's kinda a nebulous concept... that gets LOTS of attention in court
... so the cops can use your Youtube vids of you hooning it up for criminal charges, but not traffic charges... but that doesn't stop them from charging, and it's up to you to know the law and PLEAD NOT GUILTY