This matches exactly with what I have been told in the UK, that the Model S is imposing a 70A limit when it comes across DBT (i.e. "Nissan") charge points. Unfortunately most of the UK's nationwide "Ecotricity" rapid network uses these units so for now I can only get 25kW.
In the UK at least, TM have said that these charge units are being upgraded [details of upgrade, and timetable, unknown] and that once this has happened we will be able to get the full 125A.
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Drifting OT but IMO pay-per-minute is a much better model than pay-per-kWh for rapid chargers, otherwise it encourages people to stay at them even when they're tapering down to low charge rates, or after they have finished.
Of course that's assuming that the charger can actually operate at full power to start with though!