Well - I agree with you that the issue with un-insured pricing is problematic. However its done that way so to encourage everyone to maintain insurance. Unfortunately, if you are uninsured you are billed the top rate by most providers. Its however, fairly easy to negotiate the bill down to what you would have paid with insurance.
Emergency room doctors make much more than $100/hour. An Ambulance ride costs more than $500 (a 10 minute Taxi ride in an old car would cost $50). How much equipment, medication, supplies, machinery etc needs to be in an ambulance - which also needs to be maintained, etc as compared to a taxi. You're also forgetting the cost of receptionists, Nurses, billing people, nursing aids, housekeeping, all the equipment thats needed in an emergency room, etc. Nurses for example make $50-72/hour in the ER here. Then add the cost of all of those employees benefits, insurance, etc. Im not trying to justify the cost for your bill, just saying that your analysis is not taking a lot of things into consideration.
I have no idea whether it was justified or not (that you took an ambulance) - but I don't whether you're aware - Medicare does not pay for an ambulance if you aren't admitted to the hospital.
IMHO - the 'health care' you received was excellent. The cost was not. Some of the costs here relate to regulation, litigation and a for-profit system. Like you said there are positives and negatives.
Lastly, There may be thousands (out of millions) that can't see a specialist because they don't have 'the money'. But - you must not be aware of the new rules for 'charity care' that have been put through with the ACA - which mandates that hospitals and certain providers write off bills of people that show financial need (these are spelled out by the law) - so there is no reason that ANYONE would need to forgo medical care due to financial reasons in the US.