However remember this was an Aer Lingus charter and before their cutbacks!
Well Aer Lingus may have cut back on their scheduled flight standards but this was a charter and it's the charterer who says what is served (or how much is budgeted for it). If the charterer says they will have free champagne on board, that's what you get.
Most airlines have "suggested" levels of service that fit in with their logistics but on a charter they are not the final decider.