AFAIK a lot of dated bus systems have radio polling is based on signal loss. Under such a system, a stop sends out a weak stop-ID signal. If buses sit around the periphery of natural propagation they may 'drop in' and 'drop out' of a stop prematurely, which can trigger false readings. Unsure if that's how Sydney runs. Most systems now use GPS which is also susceptible to drift if not properly written (probably common). FWIW I had prior exposure to the RTA's traffic management systems in Redfern (PDP-11 still running!) ~2001, which also housed the State Emergency Service (SES) wireless system, but AFAIK no public transport.