Response time measures the wrong moment
A promise like 'we get back to you within a set time' describes the start of a process, not its end. What matters to a business is when the printer prints again, the camera records again, or the network is back — not when someone answers.
That shift is convenient because a response time is easy to promise and easy to measure. Time to resolution depends on the setup itself, and that can't be promised as a flat number.