You have to consider also that many of the oldest shards got their town decoration over many years from many sources; seer events, EM events, special events, through the governor's program, etc.
Lake Austin was one of the last shards added to the lineup so it missed out on a lot of the years when things were different. For example, on Atlantic you'd notice that in Felucca, several counselor's guilds in NPC cities are fully decorated. Lake Austin was added after the counselor program's first iteration so it wouldn't have had access to that.
Now, decoration has to be purposeful and the EMs have to be careful; Mesanna will delete anything she doesn't like as she did with the benches and other deco at Tram Vesper Bank on Atlantic.