People, however, usually choose permissive when they want a mutual collaboration that can be easily integrated into other products and services without licensing headaches and complications.
When you depend on an open-source project to succeed you're likely going to deploy developers on it regardless of its license, and while permissive licenses do not make contributions mandatory you'd probably want to upstream them anyway so you can get help on maintaining the improvements.
There are a billion examples that can be given, but we can use the classic one. FreeBSD has gotten several improvements to its networking stack from Netflix, multiple changes to its graphics stack from Sony including some AVX acceleration that didn't even exist before. Apple is also known to periodically submit a bunch of their changes, on top of already making most of the core pieces of OSX open.
Now you might ask me "and why not just use the GPL to force them into contributing?" Because sometimes they have a reason for not opening parts of their code, if they can't use a good piece of copy-left software they will just make their own, which will probably be worse depending on how big the other project was, and in the end you're just getting a shittier product in the market.