and for some time now they have been getting recycled into housing.
really though the reason the containers are cheap and available is because of capitalist overproduction. so people exporting from China consider it cheaper to sell it or scrap it than to return it to China. Ottawa thinks it they are great for housing artists.
and the housing is working out great, but be careful which one your walking into. they also make great prisons! The USA has used them to just truck people around, but ooops. they asphyxiated their prisoners. the USA has applied the modular idea to other new prisons.