Go across the seas

Once again this is a field that I don't completely understand so maybe there is a logical answer and someone can set me straight. This has to do with touring and mainly touring abroad. In the 80's and early 90's, it sounded to me like an American band would have to build up some following here before being able to get to go and tour overseas. Now the change I have seen and the inspiration for this post is that suddenly old metal bands are reforming and they immediately go to tour overseas. Anthrax, Testement and Nuclear Assault have all just reformed and each band played just a couple of dates here before going off to Europe to play the bulk of their tour over there. Are they able to play larger venues over there and ultimately make a little more money? That's fine and completely understandable if that is the reason. I just wonder if that means European metal fans are more loyal for a longer time or is it just that they don't get to see that many 80's metal bands so they flock to see them when they come? There seem to be a lot of metal festivals going on in Europe during the summer so even smaller name American bands can get booked to play at these events. Now not all metal bands are flying across the seas, in fact the strange thing is that it seems to be the heavier bands that are going over there. The more hard rock bands like Cinderella, Ratt, Quiet Riot, LA Guns and others seem to be content to play the small club circuit over here during the Summer. It seems to be the power and speed metal bands that are going across the seas.
Here is one that really had me shaking my head. Hirax were a thrash band that released two albums on Metal Blade back in the mid 80's. They were not a particularly good band and they broke up in 1987. The singer revived the name in 98 and started doing albums again on his own label. They only play a few shows a year in California and Arizona at small clubs, yet they played several festivals in Europe last year and they are going to be playing in Japan in the fall. Japan? Didn't American bands used to build up a following to go and play in Japan? Now a band that almost no one remembers will be playing there. I just can't imagine that anyone in Japan knows who these guys are that instead it's just an American metal band is playing and that might be enough for people to go see it. Not a real important topic today, but just one that has had me puzzled.