For some reason, I can't help but visualize some guy traveling from Amsterdam (or some other place where marijuana is, if not outright legal, at least not pursued in nearly the same way it is here) with a large quantity of weed in his luggage. He gets busted, probably sentenced to at least some jail time (if not substantial prison time, depending on the amount), even though back home he'd have only been facing a fine or similar. And I'm visualizing a bunch of Dutch members of some marijuana enthusiast's forum talking about how excessive the punishment is.
A bit simplistic, to be sure...but I'm still seeing some parallels.
We have punishments in this country, even some that foreigners have been subjected to, that are considered draconian elsewhere in the world.
He willfully smuggled a prohibited item into their country. As soon as they start taking "I didn't know" as an excuse, they jeopardize the enforceability of their law...because everybody can claim that one once, right?
Do I think the sentence is excessive? Damn right I do. Which is why I'm extra super careful when traveling to other countries (or even other states) to be sure I know any pertinent laws. Again, there are only a few items where you really have to pay attention or risk winding up in serious trouble...guns, drugs, alcohol, porn, etc. And unfortunately for him, ammo falls under guns.