https://www.fda.gov/industry/import-basics/personal-importat...
Okay but your statement was that there's "nothing illegal about it". You now agree that it's illegal, you're just unlikely to get caught. And if you are, you'll just lose that purchase and not face any legal consequences.
Afaik, people hide it only for some controlled substances.
Next time you play a random music video on YouTube, please look at the number of federal copyright laws you're violating. Also, if you ever drive from one state to another, check if you have any plant food with you because crossing state lines with any plant material may be illegal. And I need not remind of marijuana which we know remains highly illegal at the federal level.
That's false: it is entirely illegal.
Whether or not you can get away with it due to lax enforcement, or whether or not there are any real penalties for getting caught... that's a separate issue that has nothing to do with what you said.
Additionally, some laws are not even written clearly, and in fact are intentionally written vaguely.