I don't think they're really better than us. I think it's a combination of the following things(most of which people have said)
1) Empty short hops with fast fall. They just seem faster that way cause they're constantly moving faster. Even if there's not point to them(well I guess seeming faster intimidates the opponent).
2) As PK hexagon said, they run into a lot of set ups...and they don't care. That has a lot to do with just their play-style. Only thing is, is their representing those two players, or all of japan. Think about that for a second since this IS just two players.
3) Kinda similar to point two, they're both incredibly aggressive. Not only that but fox and falco are generally seen as faster characters with moves that are a bit less laggy. It's like putting two fast characters in a small box with nowhere to space themselves. That's what they're doing, not giving themselves, or each other space. That's mainly just because they're BOTH incredibly aggressive. The disadvantage to that is they're running into so many set ups. The other thing is, if one of them weren't as aggressive, I doubt the match would go half as fast, just because the other person would probably try and space themselves a lot more, forcing a lot more "approaching" to occur. They approach each other like...5 times in the match cause they're constantly next to each other. In most games here, a lot of characters DEPEND on forcing the other to approach.
Anyways, just some thoughts on it. I don't think they're better, so much as trying to seem faster.
Honestly I think they just miss their good ol', fast melee. =b (who doesn't though? lol)