If you've dealt with the American medical system then stories like this aren't very surprising. I'm not going to act like this is everyone's story (a lot of people have pretty smooth experiences) but it happens a lot more often than it should.
It's not unique to America. Specialists are in high demand everywhere and seeing them means you have to pass through a screen of generalists who first rule out all the common explanations for your symptoms.
But GP's point is otherwise true. It's just a job to them. They see dozens of sick people every day. There's no way to be empathetically engaged with all of them or really any of them and still be effective. It's not personal, and they aren't ignoring you. You're a bug report in their ticket system. Understand that and you'll be able to deal with the system more effectively.
If you have halfway decent insurance in the US you do not need a referral to see a specialist.
The exception to this rule is if you are in an HMO like Kaiser which force you through "level one support" (your GP) or if the specialist is so busy they require a referral to screen out the social media schizos.
This is not true, many specialists will not book you for an appointment without a referral, no matter what your insurance is. Call one up and try, some will book you but many will not. My friend was told to see a rheumatologist by an emergency room physician. The first 10 or so she called said she couldn't book an appointment without a referral from her PCP. She finally got one to see her with an ER referral rather than a PCP referral. A self-referral would have had no chance.
If you saw a concierge specialist that is cash pay only they'd probably see you no matter what though.
Yes. They don't have time to deal with hypochondriacs who just show up. Unless you are an existing patient asking for followup, or have a referral, many will not schedule you or will maybe give you an appointent six months from now.