Even if you manage to build the product (R&D) now you have to incentivize the private sector and governments to switch to the EU product. There's only few options of making this happen and tariffs could be one of them. Natural transition won't happen for many reasons.
Tariffs are not particularly different to subsidies. Effectively they are a subsidy except that consumers are paying for it more directly (being forced to pay more for inferior local products) instead of through other taxes. The source of funding and effect on prices are the most meaningful differences.
> Tariffs are not particularly different to subsidies.
Tariffs are the exact opposite of subsidies; though a tariff applied globally to all imports of a class is, I guess, sonewhat similar to a subsidy to domestic products of that class.
In what way are they so different? Both increase prices for the the consumer it’s just they end up having to pay for the subsidy indirectly through taxes and such instead of having to pay a higher price. From the sellers perspective as long as subsidies are only available for domestic producers they are even more similar to tariffs since they reduce the competitiveness of imported products.
Subsidies give money to selected market participants.
Tariffs take money from selected market participants.
They are, exactly, opposites.
They are similar in that they are government interventions in the marketplace, which under simplistic ideal-market assumptions have net costs which must be born somewhere, but at that level every possible government action is "the same thing".
> Both increase prices for the the consumer it’s just they end up having to pay for the subsidy indirectly through taxes and such instead of having to pay a higher price.
No, they don't. "The consumer", "current taxpayers", and "future taxpayers" are different-but-overlapping groups of people.
Tariffs are a trade disabler, so in general a loose-loose proposition.