Why is the healthcare community not treating add as a dopamine deficiency?

Many are: Many medications for treating ADHD work by increasing dopamine and stimulating focus. These medications are typically stimulants. They include amphetamines such as Adderall and methylphenidate (Concerta, Ritalin). But there is also a side effect of possible addiction and abuse. http://www.healthline.com/health/adhd/adhd-dopamine#research3

Much more complex: There are at least ten neurotransmitters identified with altered levels within the central nervous system in models of attention deficit disorder and its variants. The current use of certain adrenergic pathway stimulants do not necessarily treat all or even most forms of the syndrome. Much more research such as that being done with fMRI will help in determining additional Rx approaches.