I dont use amazon much these days and rarely return things but there was clearly a policy change at some point:
https://www.amazon.ca/gp/help/customer/display.html?nodeId=G...
"Unless your item is eligible for Free Returns, if you return an item using the return label from Your Orders, and the reason for return is not a result of an Amazon.ca error, we'll deduct the cost of return shipping from your refund. "