COBOL at least for me, is quite readable. I've worked with code (not in a bank) that processes binary records in a quite readable way allowed porting the functionality to C++. Comments from the people who wrote it that it wasn't that hard when you put your mind to it. JCL is another matter though. Maybe the headline should be shortage of developers who can work with poorly documented legacy code for low wages.
To me, it's readable because it usually only does very basic operations, in batch, like arithmetics, simple SQL requests and some if statements. It forces you to declare all variables once, at the beginning of the file, nothing dynamic going on, so it will never surprise you, but you won't be able to do advanced problem solving, no Google apps, no Uber, Netflix (no video processing), etc. (not saying these companies are great, just that they need stuff you can't do in COBOL85).
So it's ok at doing the most basic things. But all the other languages can do it too, and you could require compile-time restrictions to enforce constraints, you could write Rust without heap storage, allocating all memory once, etc. The compiler might get bored.