"Accessible" PDFs not working properly with VoiceOver

I work in as a software developer, primarily with Accessibility implementations.

My explorations indicate that VoiceOver completely ignores the accessibility 'tags' in accessible PDFs (more correctly known as PDF/UA files). You can find some examples of these at pdfa.org - or you can make one with Adobe tools such as InDesign or Acrobat Pro. Other tools exist which can tag PDFs for accessibility.

VoiceOver will read the text, but semantic tags such as headings or lists are not honoured. This means that the read order is likely to be distorted in arbitrary ways, artefacts such as pagination headers and footers, or decorative elements are likely to cloud the content, and browsing by semantics (jump to next heading, jump to next figure) is impossible.

The problem affects Apple bundled software such as Safari (i.e. PDF-in-browser) and Preview, but also third party PDF tools such as Acrobat Reader. It's not clear whether the problem is in VoiceOver, or whether these other apps are simply failing to expose an accessibility tree.

For comparison, fire up a screen reader such as NVDA or Narrator on Windows, and open a tagged PDF file in Acrobat Reader. For further comparison, try VoiceOver with Safari while viewing a semantic HTML5 website - most of the tags are respected (though not all).

Can anyone give some clue whether Apple is even aware of this shortcoming? Is there a roadmap for fixing it?

As an accessibility professional I can not (in good conscience) recommend Apple's products to disabled users who would benefit from using a screen reader as long as this problem persists.

Very disappointing.