> This is targeted at law abiding smallholding farmers where roadside transactions are often done in cash

Where (in NL) do you find farmers who routinely need to accept >3k in cash and are (somehow?) unable to accept electronic payments? Pretty much everyone everywhere can accept at least one form of electronic payments. That's a legal requirement for any business in Belgium, and I can't imagine the Dutch being that far behind on that ...

Even if you can't take card or contactless payments or apps, you can do instant bank transfers with most banks within the EU ("Instant Payments"), either free of charge or pretty cheap. There's no excuse for being unable to accept non-cash money. There are, however, plenty of reasons to be unwilling, but that's another story.