Well, I explained to our 4 pax that we weren't going anywhere because the toilet servicing truck had reversed into the cowl creating an air gap too big to be MEL'd.
I would never attempt to do that with 180 people. I would then spend the next 2-3 hours explaining every minute detail to every passenger when I should be doing more operationally important stuff.
David, your example of doctors explaining your test results is it's pretty much one to one, not one to 180 different people with different levels of English and technical knowledge.
I have seen a passenger demand to get off a BA B777 because of a technical delay. He became convinced the aircraft was unsafe and even when the captain explained to him individually what was going on, he insisted on getting off. Creating another 45 minute delay.
Another example.
We had a an Aux Hyd pump intermittent failure on start up. I told the pax on board that we have a minor technical issue that we need to resolve before departure.
As we hadn't moved, it comes under the MEL. There's no MEL relief. We also checked the QRH to see if there was any procedures or what the issue is inflight.
We tried a full shut down and restart. That managed to make it work. In the mean time, we'd already contacted the company about a recovery flight and to get them ready to get an engineer over or start planning a recovery.
These pax needed to be at a meeting, the sooner we could resolve the issue, the better for them. If I had had to explain the detail of the fault, the significance of the fault, the likelihood of the fault having any operational impact but although, highly unlikely we'd need said system, it is important enough that it is a no-go. While their English was excellent, I doubt I could have explained it adequately without costing a lot of time.
After landing, the pump failed completely. Although, it wasn't the pump. It was the circuit board that controls the pump that failed. The aircraft was now AOG and we went to the hotel.
Experience has shown me that while it's extremely important to not lie or be dismissive of pax concerns, attempting to explain a technical issue just leads to one question and then another and another.
Chris Whitty et al, have spent time rehearsing their message and it's been through a lawyer or two. They're rarely answering ad hoc questions. Unfortunately, even a reasonable answer/attempt at explaining stuff still has the conspiracy theorists/covid antivaxxers disbelieving his message. Imagine that response on an aeroplane? As I have witnessed, those who chose not to believe the message from the captain will demand to get off the aircraft.