Should/Do Property Managers only use Contractors with Insurance?

[Stephen Kunen]

I'm curious to know what the standard in the industry is with respect to the types of contractors property managers should be using for single family homes when they need repairs.  Is it common to require the contractors to either be covered by their own insurance for their errors or injuries on an owners property, or to have the property managers covered under their own insurance for the property managers injury on the owned property? If something goes wrong when the contractor who is not insured is injured on the property,and ordered to the property at the direction of the property manager, isn't the owner liable?

It seems the cost of repairs would go up to ensure that everyone who steps on the property is insured. Where does the balance come into play in reality? For example, is it more important to have the property manager get someone onto the property quickly to correct any emergencies that arise to prevent any damage to tenants or property?

Maybe only at a certain threshold, like apartment buildings of a certain size, does it make sense to be firm on this requirement of "all who step foot on the property must have commercial insurance/ workers comp, etc." 

Thanks