
They also have cars though? As we seen in the first chapter.
Colored photographers were invented in 1861, hand colored with special paints. And widely available by 1950.
I think this manhwa takes place at around the second half of the 19th century to around 1915 at most
Cars and horse carriages co existing at around that time

Also since she was printing copies, the first color films (although invented in 1903) weren't commercially available until around the 1930s, which is inline when TVs were ready.
So basically, I'm just finding it weird they lack other minor (and major) technological advances in a period where technology was prospering. Incidentally helicopters were also a thing in the 1930s.

Yeah I can understand where you coming from; and I can see why it’s could bother someone
But alas only the author have the answers
I think it’s was most likely the artist choice in coloring the photos instead of leaving them black and white.
It’s just and assumption but it’s does happen a lot when the manhwa artists change little (and in some manhwa not so little) details
The ML talks like such a sleaze.
And the way they have full colour photography, but no other similar technological advances, is rather strange.