Currently (as far as I can tell) there is no way for a WordPress user to have sub-users.

By sub-users, I mean that a parent user account is created. The person running this parent account can then create child accounts. These child accounts have a different login email and password, but have access to the same content, webcart, order history, and payment options as the parent account.

This would be very very helpful for B2B e-commerce websites. This is as business customers often have multiple staff purchasing. The company would be able to set up a parent account, and add the staff as child accounts.