Some shippers of high value produces (White Glove) don't even begin to prepare the shipment until they see the truck on the ground at their location. That's their priority of work. Get truck on property, prepare shipment.
At our former carrier, we were not usually told that such delays would be encountered and detention time was sometimes but not consistently paid. Over the years we came to know which shippers tend to keep us waiting.
I don't think we ever declined a load because of it. We have a nice sleeper and waiting was usually not a problem. You could say productivity was degraded because of the wait but this is expediting and you don't know that you won't be waiting at the other end for your next load. A bird in the hand is better than two in the bush.
The agents who dispatch freight at our new carrier tend to be in closer touch with and more knowledgeable about the shipment and the customer (the people who set up the order are the same people who dispatch the trucks), and if there will be a delay going in, we are told about it. If the wait is long enough to trigger detention time, the agents have brought it up before we asked.
The above mentioned loads are the exceptions. With either carrier, most loads are loaded and unloaded quickly. It is expedited freight after all.