Whatever the merits of banning single use plastic shopping bags (and there seem to be some), banning the use of such bags is a major legislative change for the City of Toronto.
Plastic bags are a significant part of shopping -- they are used and reused by consumers. Replacing the single use bags by paper will involve costs. Manufacturers of single use plastic bags will lose business and thus jobs in Canada and it isn't clear paper bags will pick up the slack.
Briefly put this is a big deal.
And big deals in municipal government aren't supposed to be made of the fly.
There should have been a notice of motion, public input and, after consultation with retailers and industry, a decision. Process matters but Toronto City Council seems unable to understand that.