The market aims to produce the most with the least amount of resources possible. So, no, we do not need to monitor how people are making money, but the negative side effects that it can bring. i.e. Volkswagen can make it cheaper, which cost you less money but in turn is ruining the environments.
We need to find a more efficient deterrence mechanism then we apply to companies right now because the profit maximizing aim forces every company or its officials to invest in illegal profit no matter the level of good governance.
Methods used for penalising companies now are not leading them to act more transparent and abide by the law. Lots of recent examples in different industries i.e. VW, Lehman Bros., BP, Siemens. The main drive for huge corporations to go illegal is the expecting impossible success from the companies.