"Hundreds of billions of lines of COBOL run in production every day, powering critical systems in finance, airlines, and government."

That number sounds enormous. If the same code runs on 10,000 ATMs, are they counting that 10,000 times?

No.

Cobol is an extremely verbose programming language, and it was used in an era when the practice of programming was much less developed. Calls into libraries were often not used, and instead any re-used code was copied, essentially inlined by hand. (With all the obvious problems that caused.)

The combination of automating complex processes, requiring embarrassing amounts of code to do simple things, re-use by copy and the fact that it was dominant in it's field for such a long time (4 decades!), the amount of COBOL code that exists out there is just staggering.