It's just a cultural difference in how they promote things. I can't really say anything about other parts of Asia but I've actually worked with various Japanese companies to promote various things (video games, clothing brands, and musical acts) and for the most part, they just want to have complete control over the process. Allowing people to take pics and video is giving up a large part of that control.
American and European companies have probably learned through experience (or possibly desperation) that even though it means losing control, having a lot of fan-made pics and videos out there ends up being a net benefit. What you lose in control, you make up for in extra word of mouth promotion, which also has the benefit of being free. But Japanese companies either haven't learned that or have learned the opposite lesson somehow. The culture in general is not as used to chaos as western cultures are, so my own theory is just that it's too difficult for them to give in to anarchy without knowing or being able to control what's going to happen.
It's completely possible that Scandal not imposing restrictions beyond the venue rules on the last US tour was either an experiment, or an acknowledgment of the different culture. No doubt they'd have been working with Sony Music Entertainment America on that tour and I've met a few of those guys and they're pretty open to letting the fans do what they want. But ultimately what they do in Japan or other parts of Asia is going to be up to Sony Music Japan and/or their management.