Despite the government's "performance monitoring" regime, the bulk of the risk of system failure is still borne by the travelling public. What proportion of passengers experiencing failure is actually compensated? If a service is punctual, but so full that no passengers can board, will the operator be penalised? If the conditions onboard are filthy and dangerous, but passengers continue to use the service because of a lack of alternative, does the drop in "Customer Satisfaction Index" affect the operators' profits?
The gap between contractual obligation and actual service delivery is where the operators make their money: perversely, they have a strong direct incentive to widen it.
Suppose that passengers could use their met tickets as taxi coupons (for station-to-station trips only) in the event of system failure. Imagine the improvement in service quality if we could pass our costs back to the operators.