"But that is not logical. It assumes that the stations are the origin and destination, "
No but the same applies to every trip by public transport - each individual journ is different
at least using the timetable it's cheap to do and the publically available.
"traipsing from home to Reading Central to King's Cross for a train to Newcastle" - there are regular direct trains from Reading to Newcastle - beats spending 60-90 minutes tryingt o get to LHR in the rush hour by car or bus