(Methylphenidate is not amphetamine btw. Other ADHD meds are literally amphetamines but I'm only talking about methylphenidate)

If cocaine had positive effects that outweighed the negatives then it absolutely should be prescribed. But it doesn't. Unlike methylphenidate - which for most people has fairly mild downsides at the doses it is usually prescribed in. It is also largely non-addictive with little evidence of long-term health damage.

Also unlike cocaine.

All in all, I'm not sure how this comparison helps.