ExXB - I do not think EZY management will be losing much sleep over the lost profit on your beer.
In my experience [only 10 or so sectors per year] I have never experienced any problems with lack of change on EZY flights - occasionally there may have been a slight delay in getting the correct change, but never a lost sale.
However, on my less frequent flights with a certain Irish lcc, it seems to be the norm to run out of change quite early in the flight: I always get the impression that there is no such thing as a £5 'float' let alone one of £60.