Your RT question: Why is the adult dose for bronchodilator solutions the same as the pediatric dose?
My humble answer: The main reason is because most of the medicine is wasted, as you can read here. When you give nebulized medicine to an adult 12 percent will get to the bronchial tubes where it relaxes them (if there is bronchospasm present). The smaller the airway the greater the degree of impaction in the upper airway, and the less medicine gets to the air passages. So while 12 percent looks bad, it might look more like 5 percent in a pediatric airway. Now that's assuming you give the medicine via a mask or mouthpiece. If you give the medicine by blowby you can decrease that 5 percent by another 75 percent. So you can safely assume most of the medicine is wasted in any patient.
Another reason is because Albuterol is safe and effective at the given recommended dose of 0.5cc or 2.5mg. Even higher doses are effective and safe. While no clinical studies were ever done as far as I've ever seen, best practice evidence suggests (as most RTs have witnessed) several back to back Albuterol breathing treatments tends to be very effective at relaxing airways with minimal side effects. For this reason, epinephrine has pretty much been phased out as a top line medicine for asthma in the emergency room. Albuterol is as effective and safer even while giving the same dose to adults and pediatrics.