Do all USB-C compatible devices have USB hubs inside of them?
No, USB-C devices don't have to have USB hubs inside. The mirroring capability of Type-C connector is provided by a multiplexer, either embedded into the controller chip (at the expense of doubling super-speed interface pins), or using an external multiplexer IC like TI HD3S3212:



Both sides of USB 2.0 data lines are simply connected in parallel at Type-C connector.