Passport Plans are very expensive when compared to other carriers

I recently added Passport plan for travelling to Canada and wanted to share my thoughts regarding the plan ... Other Carriers like TMobile , Verizon has much better roaming options available , my intent of adding passport plan is to just use Data for maps alone & for that 40$ minimum rate sounds way too Expensive ... Why Can't AT&T provide cheaper options for Roaming at least to neighbouring countries like Canada for  cheaper rates ... Since I realized it @ last moment I wasn't able to make other arrangements to cut down the cost before travelling..