Who decides upon the choice or options for number of scales to be used?

Here, there is list of standards to be used however; I feel that the scale I want to use is out of the listed one as it fits the best for the combination of sheet I am using.

Here is the list of standard scales,
1:2, 1:5, 1:10, 1:20, 1:50, 1:100, 1:200, 1:500

I am working on a overall plot plan where I need a scale of 1:2000 for A0 size drawing sheet but they say these are the standard scales to be used but I can’t…the dwg can’t fit in the listed scales….

Now what governs the standardization of scales? Why is the standardization as long as the scales are rounded off to next 50s or 100s scale factor?

Really, not able to understand the fundamental reason behind these standardized scales & the problems. Can anybody answer this?