Franglais:
As an aside, isn’t it true that only Haz Trained drivers are obliged to know the regs about quantities etc relating to Haz goods?
I’ve spotted the banana skin. 
It’s a banana skin because the rules for national DG transport vary from country to country.
Here in the UK, we have CDG 2009 (as amended) and there’s no expectation of an employed driver knowing about quantities etc.
I’m not sure about France though. 
When a job is international ( = done under ADR with no influence from any national DG rules along the way) an employed driver is also not required to know about quantities etc.
Franglais:
So could through ignorance be told that their load is not covered by Haz Regs when it actually is?
Yes, that’s quite correct, but in the UK, all that happens is that some kind of prohibition will be issued because an employed driver is not expected to know the detail of the responsibilities of the others in the transport chain.
Franglais:
A good case for a DCPC module there?
If an employed driver sat through day #1 of a standard ADR course as DCPC, then that would fulfil the lgal requirement for ‘awareness’ training which IS a requirement for drivers who carry dangerous goods ‘out-of-scope’ or as LQs etc.
They also get their 7hrs DCPC certificate, which is recognised as ‘documented’ as per ADR requirement, so that one is win-win and two birds with one stone.
Franglais:
There would need to be slack/corrupt management too, of course, for the load to go.
The beauty of this is that if the sender has lied to the carrier, the sender will usually cop what’s coming.
TBF though, ADR requires the sender to send load details to the carrier “in a traceable form” so if that’s missing or the carrier is simply careless and (for instance) didn’t ask for an emailed order for transport, then there’s possibly an argument to be had, but it won’t involve the driver.