Data exchange formats are a detail which can, often is, and quite frankly should be specified in partnership and/or vendor contracts. PDF-based interchange of structured data as part of an ongoing relationship ... seems to reflect a poor business relationships management. (And yes, there are all manner of organisations which fail to follow good practices whether on grounds of competence or malice, but generally, this…
Hm -- don't think this is the case for legacy industries. It's just what they're used to and have been doing for years
I'd suggest otherwise.
If only on the basis that PDF itself is a relatively recent data format.
"Legacy industry" to me would be IBM mainframe data formats and the like.
Which ... are their own flavour of fun.