Because the natural behavioural pattern of dominant companies is single-minded resource extraction, including from the commons which the government is in charge

Because the natural behavioural pattern of dominant companies is single-minded resource extraction, including from the commons which the government is in charge of safeguarding. On top of it the relationship they have to private citizens is extremely asymmetric. All-consuming capitalism isn't a public liberty, and if companies are in the mind of lowering costs by using cancer-inducing materials, slave work, corruption or indeed trading people's very identities, then it's in the purview of political institutions to intervene.