[ghaff]

As I mentioned in another comment, permissive licenses (MIT, Apache, BSD) are generally seen as making collaboration, especially among commercial entities easier. There are fewer gotchas to merging products and otherwise pulling in code from different places. As a matter of policy, companies are generally more comfortable making use of permissively licensed code in their own software, even if it's intended for internal use.

So you're right that the GPL provides some safeguards about code being reworked into a proprietary product and kept closed. But a lot of the industry has come to see that the flexibility associated with more permissive licenses can outweigh that. (And there's been a general shift towards more permissive licensing. Most everything in the cloud-native open source space is permissively licensed. I believe the CNCF even requires this for projects under its umbrella.)

[pjmlp]

Sony contributions to FreeBSD shows how well it works, or the various compiler vendors thar now have clang forks, yet clang is now 3rd place in ISO C++ support.