Working at a (German) investment bank still using Java 6 and Perl 5 extensively in 2018, I can assure you it's not just retail banks. Legacy technology mires are everywhere in the enterprise world and often the premia to work in those places is precisely for dealing with this kind of old technology and decades of technical debt.

In any case the same bank with Blockchain and big data lakes will also be working with mainframes and COBOL, so generalisations about technology aren't particularly useful when it comes to organisations that are so large.