I worked with some coworkers who emigrated to the USA a few years back. They all shared similar fears about the US Healthcare system. Once we showed them how it worked, how to use our insurance company's website, and how to confirm that services were authorized they had no real problems.
HN, Reddit, and the rest of the internet have become really good at sharing horror stories, but increasingly many of those horror stories are either misleading or based on old laws that no longer apply. A popular trick on Reddit is for people to post the part of their bill that goes from their provider to the insurance company and say "This is how much it costs to have a baby in the United States!". However, nobody actually pays the amount that gets billed to the insurance company. They pay an amount determined by their insurance deductible, co-pay, and out of pocket maximum. Once you go past the out of pocket maximum for a year, everything is covered 100% in network.
We even recently had new laws against surprise billing, which plugs many of the holes that created those horror stories about going into a hospital and discovering you were out of network after the fact. Technically there are still holes where this can happen, but if you look carefully most of the horror stories online are from many years ago.
Is the system perfect? Of course not. However, in practice people aren't going bankrupt every time they go to the doctor like you'd think from Reddit posts. When it comes to pre-authorizations, these tend to get negotiated between your doctor's office and the insurance company. Doctors offices know how to push pre-authorizations through if they want to put in the effort, but many some will shrug it off because it's not billable time for them.