This isn't exactly correct either. It's a combination of barriers to entry (e.g. startup costs) and how much value the developer can make vs what they're paid. If a developer makes $100k/year and can create $1 million in value, then certainly I can poach them by offering them $200k/year and still make a profit on top of that.
In many fields what prevents this is startup capital. It's expensive to get a supply chain for physical goods up and running. But if you have the business acumen and connections there is not nearly as much of a barrier to entry in the software world.
