In the US, anyone can walk into the emergency room for treatment, but people who don’t have insurance are very unlikely to participate in preventative care.
The way to decrease demand For complicated and expensive interventions to preventable problems is to increase access to preventative care.
I support increasing access to preventative care, but I doubt that will do much to decrease demand. Currently about 92% of US residents have medical coverage, and that gives them free access to preventive care services which are proven to be a net benefit.
But demand is increasingly driven by chronic medical conditions caused by lifestyle issues and local environments: obesity, substance abuse, sedentary lifestyles, toxin exposure, excess stress, lack of sunlight, etc. Those issues will have to be addressed through social policy rather than the healthcare system.
In New Zealand "poor" might be a synonym for uninsured? However my peer group is middle aged professionals (not poor) with as variety of healthcare issues. Only a very few would preventative care help. Prevention would help many of my friends. A friend with a cancer scare that keeps smoking. A friend with gout that doesn't change habits. Multiple friends with issues from drugs that continue to take drugs. All my friends and me that are unfit and eat poor diets. I've given up drinking recently but I'm most definitely an outlier.
Prevention is often the cure.
Assuming you mean prevention when you say preventative care?
Prevention and preventive care are typically classified separately, although it's a bit of a gray area. US residents on health plans receive free access to preventive services including immunizations, screening tests, etc.
But prevention is largely outside the scope of medical care. For issues like diet, exercise, and avoidance of substance abuse patients may be able to get help from a variety of other sources including public health agencies, therapists, social workers, dieticians, personal trainers, etc.
The way to decrease demand For complicated and expensive interventions to preventable problems is to increase access to preventative care.