I find the whole idea of gardening competitions to be at odds with the whole idea of gardening. To my mind gardening is an antidote to the rat race, it is about sharing your ideas and experiences. Most hippies would have already dismissed the idea that life is a contest.
No, life itself is not a contest, imo....but there are contests, and they are defined as such. Hell, all sports are contests of a sort.....etc...so if something is defined as a gardening contest maybe that is what is motivating some to garden? idk.....I amnot aware of gardening contests.
There are contests in this town for prettiest flower garden at front of home. In the tourist districts the council likes to keep all houses looking appropriate and alike so everybody does their balconies up with matching flowers. If you decline to do so you're hit with a large tax amount, the cost of the flowers is always much less than the tax penalty. Though, considering all houses end up looking the same with the same flowers, I don't know how they pick a winner. It's cute though to see everybody get out and march through the streets admiring red flowers.
https://www.youtube.com/watch?v=AABK5eY1DGc"]Elton John - Empty Garden official(Song for John Lennon) - YouTube
I am not into sports, nor am I into contests.....I was merely stating maybe reasons for your original question, so let the gardening competers answer for you then in the future.