Ultimately everyone gets "paid for productivity." Any group of physicians gets paid based on the amount of money they bring in, ie. their productivity. Some groups get subsidies from hospitals, universities or some public health funds but this still tends to be less than their collections from their billing. How they divide up this money is the real crux of the "fee for service" vs. pure hourly divide.
In a fee for service or productivity model you get paid based on the work you do. If you see and bill more patients you get more money. If you don't do much you don't make much. The pros of this are that you get paid for working hard, you don't subsidize the guys who loaf, docs have an incentive to see patients quickly and not sign out tons of charts. The cons are that guys who are very thorough but slower can lose on this system and that if you have a slow shift you might as well have stayed home.
The pro for straight hourly is that you don't have to care about volume, you just do your time. The cons are that docs tend to let stuff wait forever in the rack, there's no disincentive to signing lots of stuff out. In the hourly model the effecient guys subsidize the slow guys.
