A very common insurance industry tactic to deny access to health care is to claim that any injury or illness is the result of a "pre-existing condition." I recently bought a new health insurance policy. The salesman told me that I would be covered the very first day. However, I know this isn't true. Insurance companies have lots of ways to deny care.
If we had a national health care system, the issue of "pre-existing conditions" would no longer have any relevance. The reason is that there would be a public policy of guaranteeing access to health care. Health care would be a right, rather than a privilege.
Another side note about my current health insurance policy: while I was on the phone with my current health insurance company, whose policy was sold to me while I was self-sufficiently self-employed (by a company that supposedly caters to self-employed persons), the salesman told me to ask them what my lifetime coverage was (I was told $1 million at the time it was sold to me), the lady on the phone asked me to hold; upon returning, she told me I had a lifetime benefit of $24,000.00. There is a big difference between $24K and $1 million. In other words, if I had come down with a severe injury or illness, the total amount of coverage I would have received after the payment of my deductible was $24,000.00 over my lifetime.
The insurance companies will rely on a rule of evidence called the parol evidence rule. In theory, there is an exception for fraud, but that is very hard to prove.
Now I am sure that the contract that I signed Thursday with the new insurance company has some "weasel words" that limit their obligation (instead of the $6 million they told me).
The only way to avoid the half-truths and lies used to sell health insurance to people is to just do away with the profit motive completely. The profit motive gives too much motive for abuse. Our health is just too important to allow trickery by insurance companies to deny Americans care.