It seems like a lot of what your GP does in the US is 1. write prescriptions and 2. give referrals for patients that want to see specialists.

I've thought a bit about this, and really, I don't see any reason why it has to be a physician that does these things. Why can't we change the law to allow an RN or some other qualified but cheaper medical practitioner to write adderall scripts? Why do we need someone who went to 8 years of higher ed and several years of residency to do that?

It reminds me of eyeglasses in the UK. Prior to 1984, you had to get them through a licensed ophthalmologist. As a result, it was quite a process and expensive to get a pair of them. Then in 1984, it was deregulated and now you can go to SpecSavers and get a pair of eyeglasses for cheap. There was no reason that a licensed and well paid ophthalmologist had to gatekeep it.