The end result should be largely the same regardless of whether the externality compensation takes the form of an import tariff or user-facing retail tax. Either way customer prices rise and manufacturer/importer/seller margins drop. Tariffs are a blunt tool, but so are most consumer-end taxes as well. But coming up with the sort of Pigovian precision instrument, that attempts to fairly reflect the actual lifecycle externalities of a good or a service, is probably going to be almost impossible for several reasons.