Because 10mg of one is not the same as 10mg of the other. I'm unsure what you are not getting/disagreeing with? I'm explaining that the main danger lies in this difference, as to the average drug user drugs are sold as essentially the same, so if you are used to taking two blues (20mg) and are offered eitzolam and see its 1mg you would be wrongly enticed to take 20 to mimic two diazapam.