One day a court [perhaps in Athens] may need to decide on the use of contingency before take-off. If they find plane spotters guilty of espionage, or put you away for years because you over-ran the runway on landing, imagine your chances. Greece is not the only country where you might unreasonably suffer.
It is clear enough to me that when you commence the take-off roll, there must be sufficient contingency fuel to destination or an suitable enroute re-planning airfield. Sometimes I have assessed the likely taxi fuel to be many times the standard allowance. Where this will affect max landing weight, I have adjusted planned trip fuel on the load sheet to show legal landing weight. When the actual taxi out fuel is less than expected, and landing weight would be a problem, the actual trip fuel is adjusted by higher speed or lower altitude cruise. I have never needed to reduce payload for additional taxi out fuel, but this could result is a disagreement with my airline. However, regardless of resultant career difficulties, captain must sometimes make difficult decisions. Correct decisions are more important than paying the home mortgage.