> The Polish railways network consists of around 18,510 kilometres (11,500 mi) of track as of 2019, of which 11,998 km (7,455 mi) is electrified. [1]

As only ~65% of the polish rail network are electrified, I'm sure there are still plenty of Diesel powered trains operating in Poland.

[1]: https://en.wikipedia.org/wiki/Rail_transport_in_Poland

Technically I think diesel powered trains are just eletrical trains with a diesel generator.

Lots of danish trains are still diesel

This one is diesel and as you can see it is under overhead lines: https://pl.wikipedia.org/wiki/Plik:SA132-008_Pozna%C5%84_RB8...

Some more: https://pl.wikipedia.org/wiki/Lista_spalinowych_zespo%C5%82%...

This view was common for me some years ago: https://commons.wikimedia.org/wiki/SM42#/media/File:SM42-838...

That seems like a silly choice, since most diesel trains are diesel-electric... which is a design that can easily be modified to run dual-mode.

They probably mean diesel despite the picture chosen not making it obvious.

??? They said diesel.

Yes. They’re saying that it’s an example of a diesel locomotive, despite the picture suggesting it may be electric only.

I translated the polish language page it is on and it sounds like it is diesel with a mechanical drive.

If I understand correctly those are just somewhat cheaper per unit and some of them do run on lines that are not electrified. So it happens that a diesel train runs entirely (or often partially) on electrified lines like in the photo I gave.

I said "diesel" as a mental shortcut for diesel and diesel-electric, but certainly not for electro-diesel.