One would think that experience would make for a better barista. My spouse applied for a job at a coffee shop and was basically stopped at the start due to age. It did not fit the corporate image >:(. Perhaps they have not read the Discrimination Act properly :o.
Nor have they taken into account that the more experience one has with coffee the more one realises how much there is still to learn. As a manager I have had experience with older workers joining my industry and whilst they present some challenges with changing their practices they have become valued employees and are much more reliable that some of the younger employees (not all).
It is probably obvious that I am well over 40 ;D ;D
I hope your next experience is more rewarding - keep trying.