The confusion is the intermixing of two definitions. The first being the economic definition of a profit and the other a legal definition of profit in the context of distribution of profit. This is a common confusion.
NPOs have to make an economic profit (income > expenses). However, NPOs can't distribute profit to shareholders and the like. NPOs must reinvest their economic profit back into the organization. Where a for profit corporation does not have to. The "non profit" in Non Profit Organizations deals with the legal definitions of profit in the context of distribution.
I work for a NPO and I knock down six figures and I am one of the minions. I do make a little less than a counter part in a For Profit Corporation, but not by much. NPO does not mean volunteer nor starvation wages.
My NPO has to make an economic profit in order for us to grow. Growth is an important factor in NPOs.
In operation, there is actually little difference between an NPO and a for profit corporation other than restrictions on how economic profits can be distributed. NPOs must distribute economic profits within the organization and For Profit organizations can distribute profits outside the corporation.
Short summary: NPOs have legal restrictions on how they can use Profit.
The use of the term "Profit" in Non-Profit Organizations is confusing and can mislead the public into thinking that they don't make a profit like the other money-grubbing for profit corporations. NPOs are just as money grubbing as the rest.
They have to be in order to stay in business.
So if we were to make all hospitals Non-profit organizations, they would still be able to pay doctors the same salary they get in For Profit hospitals.