We cannot achieve consistency, so if it is important then we are doomed to failure. Why can't we achieve consistency?
There are (say) 200 universities in the UK, and perhaps 20,000 worldwide, then there are subject repositories, project repositories, library and archive repositories and commercial repositories (which may be free or charged for or a mixture).
There are data repositories, image repositories, paper repositories etc.
All these repositories are set up for particular reasons and will want to achieve different things. What the BBC wants people to do with their's is very different to say NICE or the University of Wigan. They will, inevitably, have different collection policies, different ideas on appropriate metadata standards, different methods of accessing them (an image repository or data repository will require different affordances to a text repository).
To expect any form of consistency - of language, of policy, of metadata, of standards even of legal scope will simply not work.
Indeed, I would suggest that to achieve consistency we would require working in a closed community, and even then it would probably not work.
The alternative is to embrace inconsistency and work with that.