Why would it have to be that way? Are you imagining a monopoly on all locally produced goods? Why wouldn't there be competition with a healthyish margin? Seems entirely and 100% cynical.
The point of raising a tariff on a $100 imported good to make it cost $125 is because the US provider cannot profitably sell for less than $125. The tariff doesn't magically fix the domestic provider's cost basis.
If the US provider was able to compete close to the $100 level (as they already have incentive to do!), there would be no complaint and no need for the tariff in the first place.
The point of raising a tariff on a $100 imported good to make it cost $125 is because the US provider cannot profitably sell for less than $125. The tariff doesn't magically fix the domestic provider's cost basis.
If the US provider was able to compete close to the $100 level (as they already have incentive to do!), there would be no complaint and no need for the tariff in the first place.