Most concurrent C programs of a reasonable size eventually have some kind of big global lock. The linux kernel had one for a long time and it took a lot of effort to add more fine grained locking. Similarly most large C programs have a garbage collector of some kind.
most large C programs have a garbage collector of some kind
[citation needed] - the vast majority of Linux software is C or C++ and I can't immediately think of any with GC. It's not normally assumed, everyone does explicit deallocation, possibly ending up writing their own slab or pool allocators.
On platforms like Go and the JVM, the garbage collector acts like a GIL, which is why they'll never replace C/C++.