Realistically, non-profit hospitals aren't non-profit because they are altruistic in some sense. It's because that is a tax-efficient structure for them. Given that, the participants in the structure must have a mechanism to extract money from the machine. It's a bit of a cynical view, but I believe many non-profits are organized in this fashion and their vendor contracts are the mechanism of value extraction.

Besides the big tax advantages for the business, there are programs like the 340B Drug Pricing Program - that allow non-profit hospitals to acquire drugs at much lower cost which they can then sell to patients at normal cost. Tools like this make it useful for non-profit hospitals to acquire for-profit hospitals and effectively instantly tune up their margins, which they in fact do.

That makes this just a business operating using a tax-advantaged method, somewhat like Ikea. I think the confusion occurs when people assume 'non-profit' is a public charity that gives away money. In practice, it's just a business structure with certain advantages and constraints.