Emmanuel, in the case of the builder and a home inspector this would rarely ever come into play but remember this requirement is blanket from the Builder lawyers so it covers all contractors or people entering the property. with that said, the best example would be a sub contractor (HVAC) guy is walking the not yet home owner through his install and a piece of duct comes loos and falls on his head causing injury. Well when Johnny home owner calls his 800 lawyer everyone is sues for negligence including the GC who had nothing to do with the actual install of the duct work. The additional insured coverage added on the subs policy naming the GC forces the subs policy to become primary to cover the claim and to defend the GC. the claim does not fall on the GC’s policy as his insurance company will point that out in court, thus again putting it on the sub’s policy.
there are a lot if if’s in claims but this is why additional insured’s are required by contractors/subs working on someone else’s property.