No worries, I'm sure you needed some time off from all the work in your olive business.
I'm not aware of there being colored oil here, just the diesel, but others on here might be aware if it. Maybe you are talking about diesel, and not oil also? You or someone else might have mentioned that heating oil and diesel are the same.
I can't speak for over the road truckers who use lots of diesel, but I wonder if they are subjected to inspections of their fuel tanks to make sure they're not using the off road diesel.
Yes, a lot of governments seem to be pushing folks towards a cashless society. I know in Europe the ECB is stopping the printing of the €500 note. And, in France, you cannot make a cash transaction of anything over €1000, and in Italy, nothing over €3000. There have been talks in this country in some circles to stop printing the $100 note.
They say the reason is to limit money laundering or "terrorist" activities, but I'm not so sure. Could it really be that they want force you into using electronic transactions, to, as you say, monitor your spending? I don't know.
Well, hope you enjoyed your trip to the beach, did you go somewhere like Barcelona or Valencia, or maybe even Ibiza?