In either case, I believe if you approach a business, wanting that business to provide you with service in some form, then you would be provided that Service Level Agreement, as part of your business relationship. That would not be at a retail, or individual customer level. The actual performance of the company (do they come up to the level required by the Service Level Agreement) would be portrayed in the KPI.
And, I suspect that if you are a stockholder of a company, that the KPI might be made available to you, if you request it.
I also suspect that both would usually be internal, proprietary information, and access to that would depend on your direct business/financial relationship with that company. Probably on a "need to know" basis, and would be that target company, in this case Apple's decision.