How do you know the engine works, if you aren't allowed to open the hood.
When I open my hood, there is nothing there to assure me its "working", other than a rotating fan, some noise, some heat and a big chunk of metal.
How could I know its working? It could be all batteries and speakers and butane lighters inside that chunk of metal.
Does the car move, well, lets see....
Step 1 Open door, get in car.
Step 2 insert key
(You can see where this is going)....
Nobody I know disassembles a motor in their new truck to make sure the goddamed thing runs.
Even for new an novel things like a Tesla, nobody I know insists the dealer take it appart and show them every winding and bolt.
Ultimately it comes down to "Do you really Care"? If your are a motor head, you probably do, but mostly as a point of interest.
But on the other hand, if you view it just as transportation, and it came with some kind of warranty and performed acceptably on the test drive, then for transportation purposes who cares if its 40'000 well trained mice under the hood who eat gasoline and poop only tail pipe emissions, or electric motors or an internal combustion engine, or batteries and fans and speakers making throaty sounding roars.
Manufacturer said it would do THIS, and when I tried THIS it worked, or it didn't. And it worked for all the other people who bought it for many years, and none of them came around with stories about their mice escaping en mass and killing their cat.
I don't open my cell phones either. Not on purpose anyway.