Some doctors do prescribe non-stimulants as first-line treatments to all patients and non-stimulant medications may certainly be the best first-line treatment for some patients.
However evidence based guidelines clearly indicate that stimulants are typically the best first-line treatment since they are effective in about 75% of patients. Non-stimulant medication is only effective in about 30% of patients (at best) and most of those don't have as much of a response as they do to stimulants. In general the people who do best on non-stimulant medications are people who don't respond to stimulants. Thus since stimulants are typically far more effective it makes sense to try they first and leave non-stimulants to people who don't respond since that is a very small percent. Also people who have serious side effects to stimulants and people who have a serious history of stimulant addiction are normally put on non-stimulants. However sometimes even people who have a history of stimulant addiction may, under careful supervision, do well on prescription stimulants.
We prescribe stimulants first (typically) based on both clinical experience and evidence based treatment guidelines. And for most people stimulants don't lead to problems and are much cheaper than non-stimulants. Also amphetamines are over 100 years old and methylphenidate is over 50 years old- both of these medication types are among the best studied in human history and are the best studied medications in children. Medication like Intuniv (guanfacine extended-release), and Kapvay (clonidine extended-release) have been associated with far more deaths in children than stimulants. Those same medications come in instant-release versions under brand names Catapres (clonidine) and Tenex (guanfacine) and are mostly used as antihypertensives (they lower blood pressure).
I don't know where you are getting your information but its not accurate, certainly not on a large scale.