The only reason is Canada is a buffer zone. A resource country. A place for the radioactive waste of ICBM from Russia to fall on... The one thing i like about america is that US policy of "talk softy and carry a big stick" .
The reality is the CAF is shorthanded. Canada does not spend 2% of its GNP, its more around 1.4%. The CAF has a serious lack of modern equipment (in any type of quality), with little of no depth of reserve equipment. What money they do spend also includes salary for the members of the CAF. The CAF uses CF18 bought 30 years ago (effectively at the end of their lives, replacing 138 with 88 new planes that aren't here yet.). The modern ships have big teething problems, due to bad management (overall because the government wanted cheaper, so you get less reliable shit).
Major purchases for equipment like tanks, ships, artillery, trucks, are usually budgeted by the Canadian Parliament, not the existing budget for the CAF. Canadian governments have basically killed the CAF with budget cuts and lack of response for demand for new equipment, which is very badly needed. All the material stuff the CAF is getting now, was proposed back in the 1990s, 25 years too fucken late. During the 90's the Government purchased vehicles from western star trucks (italian design), which were later found to be defective for off road work. Political decision to buy the worst vehicle, but it supplied/helped Cdn manufacturing. Effectively the Cdn Governments have severely curtailed the abilities of the CAF to respond to crisis situations. In international politics Canada does not have a big stick... just wimpy politicians.
As for depending on the US to fight for Canada, they have their own problems and Canada is at the bottom of the list. Canadians needs to have to stand on their own 2 feet and not be propped up by the US. I know most people are being Americanized by TV, and American football etc, but you still are Canadians. The idea that anybody should mention that we should just let the USA take care of our defenses, and northern sovereignty in the Arctic, shows how brainwashed some people are.
Does your neighbour ever cut your lawn? Why would you let him cut your lawn? Cause nothing comes for free. There is a price attached.