Partly. Financial applications aren't so easy to update for some valid reasons. No only do youave to implement the whole application on a new stack but also validate and extensively test them for flaws, things that have already been done on the ond application over many years.

Thats why some high end financial systems run on archaic architectures that needs to be emulated for lack of hardware.

Similarly for large enterprise applications that rely on decace old releases of OS and platform only performing security patches to mimimise breakages.

Its too simple to chalk it up as lazy.