According to the Export Import laws, any device that has a minimum
level of encryption is considered as falling under munitions type
Let's assume you're talking about the US, here, because obviously this is going to differ from nation to nation (see the Crypto Law survey map, for example). And even within a given area, Crypto is one area where the law has had difficulty keeping up and often defaults to a more relaxed state in the lack of better guidance.
If you read the summary of relaxations to the Export Administration Regulations, you'll see it's not as clear cut as you might think. In effect, the US no longer restricts the export of software (except to Terrorist Nations) based on crypto strength. (See also Bernstein vs. DOJ, which was an intentional test of the rules)
Does apple's latest oss contain that level, and if they do, has anyone
been questioned or convicted of reentering the us with the same
I'm not aware of any examples where a laptop was confiscated by the US due to the level of crypto on a commercially available OS. Why would they bother using such a troublesome justification, when they can confiscate it on a whim and demand the passwords with no justification necessary?
Traveling to other countries is much more of a problem. I have read that France, in particular, has been known to confiscate laptops with modern OSes that support strong encryption. Especially if that modern OS happens to be on a modern, expensive, sexy laptop. The kind that the customs agent wants for Christmas.