Because you’ve been fooled by the focus on those ships.

They’re not problematic because of their greenhouse emissions. Hauling stuff by sea is very efficient - by greenhouse gas emissions it is more efficient than rail freight. They’re problematic because they burn very dirty fuel which releases sulphur dioxide and particulates which are a different kind of pollutant. However, they’re released far from human population centres, and their most serious effects are localised, unlike greenhouse emissions, which are global. The environmental problems of cargo ships are there, but they are not the serious, urgent threat to human life that climate change is.

As such, they are a distraction.