This isn't accurate. Shaw has recently jumped on the same bandwagon and started enforcing hard caps with overage fees. Just go here if you want to check that:

http://www.shaw.ca/en-ca/ProductsServices/Internet/High-Spee...

($2.00/GB for each GB used above plan’s limit)

AFAIK, Telus isn't doing yet, but I've heard that this is a technical limitation rather than lack of desire to do so.