In modern Fortran, there is only really one big headache (coming from e.g. Python), and that's how hard string processing is, and how there are no generic lists. E.g. something as simple as cpnverting an integer to a string (or vice versa) actually uses I/O and writes/reads from the int to the string. (I have written Fortran code that outputs data both in JSON, CSV, proprietary binary formats and as XML at various points in time. It's not generally pleasant.)

If a hypothetical Fortran 201x added Python-esque generic lists and list/array comprehensions that played well with strings, and promoted strings to a "first class" type, I'd have a lot less reason for pulling in Python for scientific applications not involving web/graphics.