Whilst that is indeed true for the population in general, politicians are a bunch of people self-selected on being the kind who wants power.
That kind of personality is generally less trustworthy (and more on the sociopath side of the spectrum) than the general population.
There's actually a study published ages ago in the Harvard Business review about corporate CEOs (so, not politicians but in many ways similar) which found that the ones who got the job not because they sought it but because of other reasons (for example, the CEO died and they were the next in line) actually performed better (as measured by the performance of the companies they led compared to the rest of their industry) than CEOs who had sought that position and, even more interestingly, the most self-celebrating showoff CEOs were the worst performing of all (from my own participation with politics I would say those would be the closest in personality to top politicians).
Further, there are various pretty old sayings (back from the time of the Ancient Greeks and the Romans) about the best person to get a leadership position being the one who doesn't want a leadership position.
So I would say that most politicians in parties with higher chances of getting power (so, in most countries, the two largest parties) are crooked (not specifically corruption - such as getting money to pass certain laws of using certain companies for government contracts - but more generally using power, privileged information, influence and connections to benefit themselves even to the detriment of those who voted for them: a good example of crookedness but not corruption is how some US Congressmen use insider information they get in some Congressional Committees to profit in stock market trading).
Maximum profit for Healthcare companies comes from people being chronically sick as soon as possible and remaining in that state (so, alive and uncured) for as long as possible.
As it so happens, American food quality (in terms of nutrition) is horrible, the regulatory environment when it comes to approving substances for contact with humans and even human consumption is appalling (it follows the "accepted until proven dangerous" principle rather than the precautionary principle followed in Europe) and pretty much anything goes when it comes to car pollution, so people end up with cardiovascular diseases and/or type II diabetes and/or all manner of cancers of the digestive and respiratory tracts quite early, so all the Healthcare sector needs to do is keep them alive as long as possible to extract the maximum amount of money from them.