Hi, Your scope options on a workflow are User| Business Unit | Parent Child Business unit | and Organization.
So yes, it was a bit of mistake for only one business unit to be created. Once you get the org better organized I think you can use these four areas a bit better.
It's best to start with the basics anyway. Remember also that you have a large range of Security options in the Roles and the Teams as to what they can access.
So Data access is also going to effect what is happening in a workflow, especially if the workflow is set too run as an on demand process.
Curtis J Spanburgh