Can’t speak for other countries, but Sweden’s rules sound similar to Germany’s. You are allowed to monitor your own ground, but not public ground without good reason. Which makes cameras like Ring not explicitly forbidden, but you are not allowed to place them in a way which would monitor the street for example.

And regarding your question in the other comment: in Germany you are allowed to take pictures in public spaces, but you are not allowed to publish them when people are the main focus and identifiable. So you take a picture of Neuschwanstein and some random people are small in the foreground? Not important, so you are free to upload it to your internet blog. But if you film a couple having an argument in front of Neuschwanstein, then you are not allowed to upload it, because the focus is on the couple. You would need to anonymize their faces and voices.

And why is it not all countries? Because they didn’t see it as necessary to have same rules everywhere in EU, probably due to different values, making it hard to getting a compromise. Or that it wasn’t seen as important enough to bother establishing the same rule everywhere.