I've not gotten a moving violation in a rental before, but I would think that if you don't pay, the government would eventually send a notice to the registration holder, who would then pay the ticket. In this case, it would make sense that Avis would pay and then come after you to reimburse them for the cost of a ticket + some sort of service charge. Whether or not it causes issues for you in Canada, it might cause issues for future rentals with Avis.