Many proprietary software developers use open source libraries. Why is no one forcing them to open their code?

Question

open source

Let's take banking mobile software as an example. It is unlikely that anyone will argue that developers sometimes use open source under the GNU GPL license in such projects, but were there precedents when any proceedings were started with copyright holders?

Answer 1

1 , 2 , 3 , 4 , 5 , 6 , topic on offsite and more on the topic .

Answer 2

So there are different open source licenses, some restrict commercial use, others do not.
For example, the MIT license allows the library to be used in proprietary software, provided the license text is provided with the software.

Answer 3

Many proprietary software developers

You didn't name a single example.
Never
Banks are so poor that they use open source?
Have you listened to Underwood's song about Crimea, haven't figured out that there are 100,500 different licenses and an Internet anti-globalist has awakened in you?