Electrons Flow in cables
In a ring, all communication is really one-directional and point to point.  The ring topology only happens because each node has two ports, one for receiving from upstream and one for sending downstream.  When a node does not consume a packet (and sometimes even when it does), it re-transmits the bits it receives from the upstream port to the downstream port.  Electrically each link is point to point, making termination easier.

Even modern ethernet is all point to point.  The illusion of a shared network segment is created by hubs and switches.  Hubs merely pass on what they hear on one port to the other ports, and are not really used anymore today.  Switches look at the destination addresses of packet and pass them on to specific ports as appropriate.  Everything is point to point again, but this time bi-directional at the cable level at least.  Inside each cable are two twisted pair, one for carrying the bits in each direction.  That actually makes each pair point to point and uni-directional.

The original ethernet and then ThinLan were true busses, but you'll only find those in museums today.  True busses are still in use, with CAN being the top example.  However, it runs much slower (up to 1 Mbit/s) and is for a different purpose than general networking.