Probably not. But precision is expensive. A 3A +- 0.1A fuse will be more expensive to make them a 3A +- 6A fuse. And of course a customer will be upset with a 3A - 2A = 1A fuse so they really make a 9A +- 6A fuse and sell it as 3A.

So if you are "lucky" you can pass 12A though it no problem.

(Numbers make up for illustration.)