Isn't the idea of ENCTS passes that usage is charged to the county the journey starts from - hence issues in places like Cumbria, Devon and Cornwall, where they are paying huge amounts for visitors to use their services? Or is the situation different in London with the Freedom pass/ENCTS crossover?
If my understanding is correct, all ENCTS usage in London would be charged back to the boroughs (whether or not they charge by location of boarding is something a local person would have to answer), but for places like Hertfordshire (e.g. service 292) or Kent (e.g. 96, 428, 492), pass use would be charged to the respective county until it reached the border.
I believe passes are also only valid at their time of validity in the starting area (so you couldn't use a Freedom pass to travel from Kent into London, but you could from London into Kent, at 8:30am, for example).
Happy to be corrected on any of the above by someone in better know.