The advantage of individual cleaners is price, while the advantage of companies is a certain guarantee of quality. A company, however, usually has much more overhead than an individual and as such will have to charge more. They don't have a choice.
Now, Cleaning 3.0 companies (such as Maids Made) have lowered the extra overhead to negligible amounts. Hell, I think that we have less costs than the majority of single people cleaners out there. Because of this, we are passing on the savings to the customers and offering a high quality cleaning service at individual contractor price.
/end shameless plug!