I am well aware of all of your other arguments, as I was a Psych major who specialized in perception.
I'm of the government's stance on this currently: I think it's a real phenomenon, I trust most qualified eyewitnesses especially if it is in concordance with radar data, and I refuse to concretely claim anything further. And it is a mystery.
But I AM free to speculate.
I could claim something like "assuming there IS some alien intelligence controlling these hyper-performing craft... if another intelligence was advanced enough to even make it here in the first place, ostensibly they also have fairly full control over all elements of the interactions with us, which includes not showing themselves outside their craft", but this is also the Conspiracy Fallacy. Two thoughts on that though: The Conspiracy Fallacy does not disprove conspiracies (which is why I am openly stating this is speculative). And secondly, this also means that (if this claim is at all true), they are likely voluntarily showing themselves at some "pace" as to not overly upset us. Why that? Well, perhaps you've heard of systematic desensitization (https://en.wikipedia.org/wiki/Systematic_desensitization) as a treatment for phobias? That might be going on here. And it's apparently working, since nothing crazy's happened since the USG openly admitted this is real. This is a far cry from the Orson Welles' "War of the Worlds" broadcast days.
So, no. I can't say it's aliens, at least rationally. But I do speculate that. ;) And honestly, I think it's fun to think that not only might we be not alone (wouldn't that be amazing??) but that we're kind of in a galactic kindergarten. ;)
Why has nobody ever taken a photo of these alleged aliens?
It's up to the proponents to provide convincing evidence. "But I saw it with my own eyes!" is completely unconvincing. Anyone who claims to have never misinterpreted anything they saw is just not credible. Optical illusions affect everyone.
Sane drivers know this and take it into account when driving, that's why it doesn't cause (many) accidents, and is so ordinary nobody bothers to report it.
The human visual system is full of compromises and kludges that just happen to work well enough. Did you know that your eyes have a blind spot that your brain fills in for you? By guessing? That magicians rely on all kinds of errors your brain makes in perception?
But no, it must be aliens!