Consider that in some ways, the control that the government exerts over the players in many industries has reached a degree such that the businesses are no longer able to experiment with new business models and new products.
Also, many industries are so insulated from competitive pressures that they need not behave like businesses. Price supports, protective tariffs, paying farmers not to farm, etc., prevent businesses from reacting to market demands. And those businesses become so dependent on the supports that their arms are twisted into doing business the way that the gov't demands. These subsidies always come with conditions, and that's just another way of saying that the government is assuming control.
The airline industry certainly meets both of these criteria. They're incredibly regulated, only allowed to offer the services that the FAA allows, and subject to the conditions of the DHS. The medical industry is in this boat as well, particularly given the reliance on Medicare/Medicaid that dictates its actions. I could go on...
But beyond this, it's not too hard to identify nationalized industries. Just take off your blinders -- there's no reason that *any* enterprise needs to be undertaken by government. Without debating whether or not these things SHOULD be in the government's hands, please just admit that they ARE:
- Highway building & maintenance
- Retirement planning
- Disability insurance
This is just off the top of my head. All of these enterprises have historically been in the hands of free enterprise at some point, but have been nationalized here in the USA.