Why can't I buy international songs in my iTunes?

Why can't I buy more international songs in the U.S. iTunes store??

I am half Japanese, so I know and discover more Japanese artists and songs every year. But when I search for the song/album/artist in the U.S. iTunes store, it gives me these lame (and sometimes not even the actual song, or like, covers or music box versions of the song) excuses for what I was searching for. Or it lists some of their albums but not all... It really makes me mad! Because I feel like iTunes should have like, every song and artist listed no matter which region or country you are using the iTunes store through so that everyone can get whatever they want.

And my problem with iTunes is only when I want to buy international (in my case Japanese) songs...

I also tried switching regions/countries to see if that was my problem. I was hoping I could easy-breazy switch so that I could buy the songs on the Japanese iTunes site, but I guess not. It said I had to use up my whole balance first.... I have like less than 50cents left, I cannot buy anything with that...! So does this mean I can't ever switch regions unless I figure out a way to methodically get it down to perfectly $0....? ***

I hope that there is something I can do! And not result in IDS.

P.S. I hope everything made sense, even though I feel like I answered my question by myself a little already... :3