What I mean by "It's easier when you're neutral" is that, for better or worse and with mixed results, America steps in militarily when needed. Not that other countries, including Canada, don't, but when you consider the two World Wars and many conflicts since, it's been good to have a superpower that's committed to freedom. That commitment means having a large and complex military machine at the ready, which of course costs a lot of money.
America is also an incredibly diverse country with the kind of racial and ethnic history that I don't think a country like Canada can match, and our history has strengthened us AND has made things incredibly complicated. I think it's easier - not easy, but easier - to commit to certain policies when you don't have the same history, and when you're not counted on to be the last democratic superpower.