Getting a prescription is only half the battle. In the US, you can't have more than a month supply. Maybe you're lucky and your doctor realizes this so writes you a larger than necessary prescription, but for most vehicles (extended release) it's not an option. Many people horde a backup stash of pills.
This means you have to get your prescription filled within a small window at the end of your previous supply if you want to avoid running out. You also can't have a recurring prescription, but a rare doctor might renew a prescription over the phone. And even then, you have to deal with pharmacies running out last minute, travel impacting your refill schedule, and health insurance coverage for the otherwise ludicrously expensive medication.
A nightmare process that someone with ADHD cannot go through indeed.