hugo this is not a bug, so i`m gonna remove the bug tag
think the module mostly deals with invoicing aspects per general, as accounting if you wanna call it. while the tickets have just the billable status for easier invoicing decision. like if an admin will set the ticket as billable, then the technician would know to bill for the work is doing, or if the ticket was billable and technician did not invoiced, then the admin can follow up and double check all aspects of the ticket.
@wrongecho just a quick one on this, i think we can add a future feature, if the ticket is billable, dont allow the ticket to be closed unless ticket is invoiced. this will then make the life easier for admins who will set the ticket as billable and then assign to other technician. just an idea