To say unions are less efficent and more expensive than the private companies is a sterotype. For example, unions aren't about making profits, thus they can pay employees more and still be less expensive than for-profit groups. As there isn't a 'private sector' of transit employees, we don't have a baseline for comparision.
It is union management and company management that creates the enviornment that everyone works in. If that's an atmosphere of hostility and blame, what progress will be made? If we were to change that to an atmosphere of cooperation and innovation, the Union would fade to the background. Would you work 13 hour days (split shifts with a 4hr break), 5 days a week for $55k?
I know consultants who do design work for the TTC charge around 3-3.5x the cost of an employee's time. So even at minimum wage, a private-for profit company would increase the costs to the TTC.
Yes, unions encourage higher wages and protect even marginal workers, but don't hate them because they are filling the role they are entended to fill.