If you are producing data then exposing it in a nice programmable format is an extra cost and generally provides you no benefit. It usually hurts you, if people stop visiting your site and see fewer of your ads!
This is "really" a problem of incentives. It is usually not possible to capture any of the positive externalities of exposing your data. So maybe we could convince everybody in the world to switch to using different browsers with a native micropayment system; that might incentivize everybody to release all data as clean machine-readable tuples.
What I'm saying is, the phrase "Better UX and data quality" ignores just how hard that solution really is. It turns out training an LLM over most of the internet is _easier_ than global coordination.