Testing is only effective with effective people
All right, look: if you have an incompetent group, testing doesn't really mean anything.
The group has to contain competent people in order for the whole development cycle to succeed. If you have idiot developers and idiot testers, you have trash output. If you have bright developers and idiot testers, you have someone rubber-stamping code as it goes, with the product being spotty. If you have idiot developers and bright testers, then the testers find all sorts of bugs with no hope of them being fixed.
The only time this works is when there are enough bright people in the group for the entire product cycle. You have to start with good design and architecture, good implementation, and good testing. Fail in anything, and the product is going to have serious problems.
When it comes to embedded devices, the testing can be horrible. Imagine your company white-labels a device. You receive the device, test it, and it simply falls down flat. So you send the bug reports, and can only hope for a fix. And of course, the device doesn't have any interface for automation. Maybe it's embedded Android, or maybe it's embedded who-knows-what. All you know is that you can't humanly scratch the surface of the bugs that are there, yet because your company's name is on it, you're on the hook for what that thing does.
Yes, it would be great to have an AI harness. But of course, all of that has to be set up. And you still need competent people to do that.