I work in IT and in similar systems, the reason from my perspective to do this is when a ticket comes in a timer will start ticking. Whenever the ball isn't in our court that timer is cancelled. If i set status "pending user" and throw a dumb question it is paused. If more than 10% or whatever amount was agreed on when the contract was signed our company has to pay for not living up to expectations.

There's a lot of rule bending to make this work in our favour.

Of course different providers will use different metrics like how long before the ticket was handled etc.

Online retailers, too. Item goes from ordered to processing to shipping in a half hour. Takes a week or more to go from shipping to shipped.
Item can’t be cancelled without a restock fee if it’s in shipping — which is fine (I guess) if the item takes the provided time estimate to arrive.