Hi Al. In a previous life I owned a 104 year old Irish Pub (I retired from DoD contractor work). There is no real answer to your question.

1. It depends on the size and shape of the glass for starters. There is an entire science dedicated to glasses in bars that the general public isn't aware of. The height, width, thickness and general appearance are chosen carefully but are an illusion to the actual amount a glass holds.
2. It depends on the bar manager and how strict they are regarding portion control.
3. It depends on the actual price of the wine/spirits being poured. More $$ usually means less to the consumer.
4. It depends on how the bar tender is feeling that day.
5. It depends on what portion they can get away with. In high end places the clientele would never complain they were getting short pours, it would imply they were cheap. In my old bar I would hear about it for sure:) A large wine glass implies that you could enjoy the nose of the wine and you are a wine snob.....right or wrong. I have two brother in laws that always try to impress me with both their wine knowledge and the price per bottle, neither of which I give a fat rat's petute about.

My experience is that most sailors/boaters prefer decent quality wine AND full glasses.