Amazon has a physical presence or place of operations in Canada so they must collect GST for all of Canada and PST in the provinces where they operate. Where provinces have HST (GST+PST), it must also be collected in all of Canada.
Netflix does not have a presence in Canada so they are not required to collect GST, PST or HST. However, Canadians are required to submit them.
Canadian individuals and businessess are also required to submit income tax for overseas earnings but they often don't and use tax loopholes like registering companies anonymously in sheltered countries or moving earnings to tax havens.