The scenarios you describe would be possible to do automatically as well and I'm going to look into doing something like it in the future!
The reason why I chose photos instead of screenshots was that the in-game graphics are not yet that good and because I wanted to make it clear to the users that these are real trains, not some product of my imagination. Screenshots are obviously much easier to create than finding suitably licensed relevant photos, so I'll probably start using screenshots in the user interface at some point.