beers in america made do require a hechsher because they often add a treif ingredient to make a head.
Which ingredient is that? I’m fairly certain that you are either (i) wrong, or (ii) saying something as fact that is actually a minority opinion.
european brewers never add anything to their beers. its against the law to put in anything besides malt and hops and water.
And yeast. And a bazillion other additivis, like isinglas.