While the OP's AC shower experience and lack of clean towels plus the dirty ones left behind may be a small issue to some, and it may have been a lack of attention by the prior user to return the card, I also think the point jsfrSE was making was that his experience at the AC showers was a sharp contrast to the long-haul CX flight he had just arrived on.

It also makes me wonder why AC doesn't even have a small acknowledgement of a birthday for MMs etc (well, maybe they do for MMs).

There are likely very few flights where AC would have an MM onboard on their birthday and wouldn't it be great to receive a card and a small gift etc.

AC knows who these customers are, they certainly know personal info, they know when these customers fly.

Hmmmm.