As someone who works for a bank... no, not in my experience. What is a problem is that the last time a lot of code was touched may be 5-10 years ago. That code

As someone who works for a bank... no, not in my experience. What is a problem is that the last time a lot of code was touched may be 5-10 years ago. That code may have started being written 20-40 years ago. It may well have been maintained by people who think "if it was hard to write, it should be hard to read" or "documentation is for the weak". It definitely will have been written when the cost of a gig of memory and storage was many orders of magnitude higher than today (indeed, last time I priced memory for a mainframe, a Z10, it ran to $10,000 a gig); hence terseness in everything from table and column names through stored data and everything else was prized. Dropping from COBOL into assembler is not uncommon for critical path performance. Making any changes will be a week of coding and three months of working out the what and why of the code, because the last person who worked on it retired a couple of years ago.