Conclusion: no measureable ROI. In fact, the enterprises have no idea where or how to begin measuring (we don't either tbh). We are still early. Keep buying our product, so we can find out, together.

What is difficult about measuring RoI? Time scales?

Sounds like a question the AI labs should answer. After all, they all say they sell artificial intelligence.

So why does that intelligence seem to have a hard time even showing its own usefulness?

Shouldn't it be the users that need to do any RoI measurements? Not sure you'll get detailed data from them easily.