What are the policy reasons for imposing strict liability in vicarious liability cases?

Robert Stevens identifies four main policy reasons for this strict liability. First, to encourage an employer to be more careful; second, that an employer will have 'deeper pockets' i.e more money to pay compensation; third, that it spreads the loss across a number of people in the employer's business, rather than it falling on the one defendant; fourth, the idea of 'enterprise liability'- that if you benefit from the activity, you should also bear the burdens of it.

However, Stevens identifies problems with all of these reasons. Strict liability means that even the most careful employer will be vicariously liable for the actions of their employee. If we want the 'deepest pockets' to bear the loss, then surely the deepest pockets of all belong to the state- so why not have a government scheme of compensation? The idea of loss-spreading cannot work where the 'employer' is a single individual. 'Enterprise liability' doesn't provide a satisfactory answer, because a not-for-profit organisation may also be held liable even though they don't 'benefit' in the same way from the employee's actions. Despite these problems, judges frequently refer to the policy underlying vicarious liability decisions, for example Lord Phillips in Various Claimants v Catholic Child Welfare Society [2012].