I think that it's hard to draw a logical link between someone buying a quadcopter and Wal-Mart and doing something irresponsible with it because they aren't a dedicated member of the RC community, and a commercial entity using a RC planes/helicopters in the course of their enterprise.
In the former case, it seems that the issue is that technological advance has removed the barriers to entry that have historically regulated access to these machines to those who have a responsible and dedicated interest in the field. Perhaps regulations are needed as to the capabilities and safety features of "cheap" RC craft, similar to how there are limits on the model rocket parts you can buy at the big-box.
In the later case, for-profit companies use all manner of potentially dangerous equipment, often in places where it might come in contact with the public. Imagine if the DOT prohibited taking a vehicle on the Interstate for a commercial purpose; it would be absurd. Instead, you can drive the company pickup just the same as if you were driving your own. Then, for larger vehicles or those being used in a non-standard manner, there is a system of commercial driving licenses and insurances.