alt Hacker NewsSoftware licenses aren't enforced through litigation as much as they are enforced through the _threat_ of litigation and legal risk. In other words, pretty much every company pays lawyers to minimize legal risk. Those lawyers inevitably look at all the contracts, agreements, and software licenses, and tell the C-suite what to do in order to keep their legal exposure as low as possible. "Don't violate other companies' IP," is pretty low-hanging fruit in those conversations.
It is a very rare (and ballsy, and perhaps incompetent) company that ignores their lawyers' recommendations to adhere to the letter of all of the software licenses they are bound to.
Normal software is copyrighted. Model weights don't seem to be copyrighted, as another comment pointed out here: https://news.ycombinator.com/item?id=49073127
If weights aren't copyrighted then there's no IP to license, other than the bit of software that runs the whole thing and it's probably not too hard to write that yourself. There might even be open source reimplementations soon.
Lots of companies are willing to push the boundaries of IP when there's a gray area. One example is Google's implementation of a Java API when they made Android, for which they got sued, and won their case. Another example is the AI companies training their models on copyrighted material.