You're simply underinformed.
it's possible to have service level agreements about things like uptime of a service that is wholly managed by a provider that are sane. Things like how much is guaranteed before payment is reduced or no longer expected.
However that's not what IT departments deal in. No IT department starts losing funding if they fuck up the DNS infastructure for 2 weeks. No IT department loses its funding if they fuck up the spanning tree for the 5th time in a single year.
SLAs in this context are about "we promise to write a pointless reply email within 1 day" and such, which are the VAST MAJORITY of SLAs in the overall computing and IT industries. And if you had any breadth of experience you would know that.