> But then, does this mean anyone can ask for the source of closed-source software that use GPL code, like the ones below? (I just dug two random examples).

If their software is a derivative work of someone else's code then they can't distribute their software without a license from the copyright holder of that code. In the case of the GPL, that licenses them only to distribute their code under the GPL. If they are distributing their software other than under the GPL, then that is copyright infringement (in the same way as if they had made a derived work of some non-GPL code and distributed that), they lose their license, and any holder of a copyright on the code that their software was a derivative work of could sue them for copyright infringement. (In theory they sue for damages; in practice the copyright holder of GPLed code they made a derivative of will usually settle for compliance and an agreement to have their future releases audited).

What constitutes a derivative work is a question for the courts. It's generally accepted that any program that uses a library is a derivative work of that library, and a program that invokes another program at arms length or via a standard interface is probably not a derivative work of that program. The exact boundary is unclear; there's a case to be made that a program that is tightly coupled to another program and invokes it via piped commands might still be a derivative work even though it's not shared objects.

The LGPL is an entirely different license from the GPL.

I didn't look at all the LGPL/GPL code they are using, but your understanding seems correct.