Those studies are of workers using company provided AI.

They call out the MIT study in the article, which found very low adoption of corporate AI initiatives.

However if you read that study, they found that almost every worker uses AI heavily, but they just use their personal AI account.

Again, people are using their own AI to benefit themselves, it makes the most sense. Using company AI shows that the AI is doing xyz, and maybe perhaps you aren't that valuable. Using your own AI makes it look like you are doing xyz, and you are the valuable one.