This article about an important Supreme Court ruling in 2017 clarifies the situation:
https://consumerist.com/2017/03/22/supreme-courts-ruling-in-...
1. US copyright law prohibits "useful articles", like clothing, from being copyrighted.
2. However, as that article points out, "decorative features of a uniform should be treated like two-dimensional artwork". Look at the example on that article - it's basically some abstract stripes and triangles that were seen as deserving of copyright protection, much less than a sweatshirt with a pink "Barbie" logo in recognized font on it.
3. Beyond copyright, you can get a design patent on articles of clothing. Christian Louboutin is famous for their red soled shoes as well as their "spike" sneakers, and they're suing other companies making red-soled shoes and sneakers with spikes on them. We'll see how far they get.
In any case, my original point in posting this and the other examples is that the first comment I was replying to, at least to me anyway, was implying that the fashion industry has thrived without the need for IP protections. On the contrary, there are a TON of lawsuits in the fashion industry related to IP protections where one designer is accusing someone else of "ripping off" their designs. The mechanics may not be exactly the same as with written words but the effects are identical.