I don't believe in the whole tipping percentages thing. If me and my buddy go out to a restaurant, and he orders a $10 burger plate and I order a $25 steak dinner, and we both get the same service, why should I give more of a tip just because my meal cost more? That's just stupid.
And I don't think the laws in Canada are the same. Minimum wage is minimum wage, doesn't matter the job. So a waitress will make $10.50/hr, and if one table gives her a $10 tip, well she just made an extra $10/hr. And that's just 1 table. Most waitresses are working 2-3 tables or more at a time. So they could potentially be making like $40-50/hr.