Plenty of specs are open and require payment to obtain documentation.
You've obviously never needed actual ISO or IEEE documents.

The open comes from them being available AT ALL. The non-proprietary comes
from being available for consumption AND being developed in an open fashion
by members of it's committees.

Open and non-proprietary doesn't require being available 'free of charge'.
And it's just bull**** to whine about suing someone for 'false advertising'.

Besides, if you're a serious developer then $4k is a drop in the bucket
cost-wise, as opposed to the R&D costs of inventing something equivalent.

But that said, yeah, it'd be great if the docs weren't held hostage for such
an exhorbitant price.