I think it's likely that "may need someone else's permission" refers to things like waivers for using a person's likeness, or so-called moral rights. These are

I think it's likely that "may need someone else's permission" refers to things like waivers for using a person's likeness, or so-called moral rights. These are not usually included in the bucket of things most people call "intellectual property". It's more like, if I have a picture of a person and use it to sell something, some people may conclude that the person is endorsing that good. There are many countries that have separate laws concerning what you can and can't do with images specifically.