In Calgary you have to get a busking permit for the venue you're going to play in. E.g., a permit to busk in the Eau Clair Market doesn't allow you to busk on Stephen Avenue Mall and vice versa. Some areas don't require permits -- it's all up to the individual area associations. The city government doesn't take a hand at all. If you're busking without a permit, it'll be the local security rent-a-cops that move you along, not the city police.
I've never busked, but my son's band do it a lot. I'll ask him what kind of money they average.