I dont have a lathe at all, so my opinion might not amount to much on this subject, but competitions with regular entrants judged by experts are usually self defeating. In a very short space of time people know that the winner will be one of a very small number of very skilled turners.
The "i know I wont win so I wont enter" syndrome has been around forever.
I have a couple of suggestions, based on other non woodworking sites that i have been a member of that might get people posting pics., which I think is mostly what this thread is about.
First, a separate headed thread for a monthly picture of whatever youve made. Forum wide, not just turning, titled to attract attention to it.
The entries to be voted on by all forum members purely on which one they like the best regardless of talent or composition. One member one vote, highest number wins, no prizes, or very small prizes. Anything that does not win can be re-entered each month.
Second, create a "show and tell" thread (you have to give americans their due when it comes to pithy titles).
No prizes, no voting, just a member puts up a pic and says "I made this". He (she) can then ask for comments and criticisms (or not).
I am on a mostly american wood forum and often post pics of my boxes there. I'm an amatuer, but am happy to show and receive comments. Last year I posted a box on that site and got about 40 replies, all of them encouraging and complimentary. I posted the very same pics here and got ONE comment, picking a fault with the joints. The fault was there, and the comment was justifiable and noted, but that shows maybe why most people here are reserved and "camera shy" when it comes to pictures.