[DrScump]

  Trans fats are more or less banned in the United States

Not at all. They remain common in packaged food, especially in the form of artificially hydrogenated oils.

Even butter has some naturally occurring transfat.

[maxerickson]

There's (almost?) no one using partially hydrogenated oils anymore so the story with packaged goods is about the same as butter, in products using fully hydrogenated oils there's a small amount that would be difficult to remove.

The granola bars I eat switched to unprocessed vegetable oil and upgraded their packaging (better oxygen barrier). A lot of products did that.