My German is pretty bad, but I think the explanation here is about why they aren’t smiling? Just leaving this here in case anyone else is curious: In the early days of photography, people didn’t smile for pictures because they had to hold a pose for several seconds. Easier to remain neutral.

Yes. Also, paintings mostly had a sincere face, that also influenced photography at the start. Smiling on photos only became popular in the 20s and 30s due to advertising photos.

Oooooh interesting! I never knew that last part. Crazy how much marketing has shaped our lives, both in the past and in real-time.