some questions about the USB expander devices.

I’ll buy some USB3.0 expander devices.The question is about USB expanders devices(i.e. extend one USB3.0 interface to several USB3.0 interfaces).
Nowadays,in the market,can all the USB expanders devices actually extend one USB3.0 interface to several USB3.0 interfaces?Put it another way,can I say that in the market,it doesn’t exit such USB expanders devices,some of whose extended USB3.0 interfaces don’t work at all,i.e. if I connect one USB camera to the extended USB3.0 interface,actually tx2 doesn’t recognised the camera just becuase the USB expanders device.

Or probably the following situation:I bought a USB expanders device which extend one USB3.0 interface to two USB3.0 interfaces.And the two extended USB3.0 interfaces are intended to connect one USB camera respectively.However,one camara can only share just very few bandwidth because of the USB expander device,so it can’t satisfy the transfer rate of the camera.Does this situation exit?