Gaara has fought people much faster and stronger than anyone in Avatar, like Rock Lee moves at supersonic speed as a genin. Nothing even moves that fast in Avatar, much less bend elements at that speed (well there is lightning, but even then lightning jutsu is pretty common in Naruto). Not only that, they assume she would have absolutely control over his sand, which doesn't make sense because even in Avatar when two people who bends the same element go at it, they have to basically compete for control over it. Gaara made sand out of basically a whole forest and can harden it to basically to tank explosions. Like I don't know what the point of posting that gif when Gaara literally had to do that except with a mile wide area and he had to make it really deep too. I don't even like Gaara but it's pretty obvious the scale of the stuff he works at is much larger and even does things more intricate like creating clones and a giant body for the tailed beast. She also had an issue fighting in sand because it messes with her sense, which Gaara can create on the spot.
Gaara's a little inconsistent on how well his sand defenses can protect him, and they used post-Shukaku Gaara for that fight. Also her sand issue was fixed by the point where that GIF takes place. That's why she's able to do stuff like that. They didn't assume she'd have absolute control, just enough to deflect, which is typically how fights in that show go.