Maybe she’s wealthy enough to be able to not go bankrupt for her treatment, and staying around friends and family and avoiding travel are all good ideas for someone with brain cancer?
The situation you're referring to applies to the 11-12% of Americans who have no health insurance. An unfortunate situation that the US should work to rectify (ideally with a universal option), but hardly the third-world situation most Europeans envision.
Max annual out of pocket includes copays, do you don't need to cover both separately, but 1000-4500 is not the range of out of pocket maximums. The limit for a bronze marketplace plan is $7,300 for an individual plan or $14,600 for a family plan; the average for bronze marketplace plans is about for $12,000 for a family plan. And that's for things the plan covers; there's obviously no maximum for services excluded from coverage.
Sure, your actual personal plan maximum depends on your plan.
The range of maximums that characterizes healthcare plans in the US, however, does not depend on your plan, and it definitely does not top out at $4500/yr for even an individual plan.
I pay nearly $400 a month and my annual max out of pocket is $7,350 with $7,000 deductible.
Disconnected from reality of what it really costs middle class American's for plans out of pocket.