Did you not see my other suggestions for those outside London? Car share, coaches, local buses?
Did you also not see me mention driving to where you can get a bus to the Tube station, which would get around the parking problem.
Did you not see me point out that these alternatives would be inconvenient?
It IS possible to run a reasonable train service with lower fares as can be seen in mainland Europe. And many of these countries are even less in debt than the UK so low rail fares haven't bankrupted them.
For the price of a middle distance season ticket in GB, you can get UNLIMITED travel for some rich Western European countries.
For the price of a chocolate bar you can get across most European cities!