I'll answer that question. I have been in this hobby for 45 years and have attended many seminars (and I still can't get it right all the time), demonstrations, conventions, and shows. I went to a show in St. Louis a few years back, in which they had a class called "Aquarium Beautiful". Some of the top designers in the world, including Takashi Amano, Rolf Lingensturm, and others were there to show off their talents and give seminars. This show was sponsored by FAAS and TFH among other big contributors to the hobby. All of the "big hitters" were there. To say this was a premier event would be understating the fact by a long shot. Anyway, to get back to the question at hand. Some tidbits for your inquiring mind: A) All of the "Aquarium Beautiful" tanks were auctioned off to attendees of the convention. This is not always the case, but does happen at most events, and as I understand it, does happen frequently at major shows. B) Almost all shows have a limit on the tanks' size. Many put the limit at 30g, although I have been to shows where 50g is the limit as well as some limiting tanks to even smaller sizes. The reasoning behind this is to create a level playing field and to make things a little easier for the competitors. It would be alot of work to put a 125g diorama together in the short time periods between registration and judging and an impossible feat. To me, that fact is simply amazing. So much beauty in such a confined area.
The exception to this would be those tanks decorated for a photo shoot only. The lives of many of these incredible tanks is short lived as they are usually torn down following the shoot.
I hope I have answered your question in a concise manner albeit long-winded.