Naturally individuals can cross the border and get cheaper stuff. But in the grand scale of things, that's irrelevant.

IMO tarifs are preferable to subsidies. Subsidies encourage over production, plus still places the industry at risk. Tarifs just incentivize purchasing local. Plus for whatever revenue there is, it's an income to govt coffers. Whereas a subsidy is an expense. And ultimately the cost is born by the consumer of that product, not the wider tax base.

So, well targeted, it's a more effective tool than a subsidy, and much less prone to waste or corruption.

Put another way, a tarrif is much cheaper than a subsidy (and tarrif makes for a better outcome.)