"Also consider this: 90+% of humans walking around have high-definition cameras on them at all times. Governments have blanket satellite coverage of the entire earth."

Neither of these things are true though. Satellites have a limited amount of the planet they can cover at any given time and though there's a lot of them there isn't enough to observe the whole world constantly in exact detail 100% of the time. Also the idea that such a huge population of humans all have quality cameras is also not true, for one thing most standard cell cameras can barely see in the dark and usually can't make out the details of something even a mile away so the cameras themselves on a fairly high end phone aren't particularly good for spotting things like UFO's. That aside not as many people across the globe have 1k dollar phones as you assume, it's mainly in western nations and some asian ones like Japan where you can expect a high degree of the population to have them but even then the more rural the area the more likely people are just gonna get cheap flip phones or old model smart phones as they don't want to waste money on things and so the cameras are even worse.

The idea by skeptics that 'everyone has a camera and cameras are better than they used to be so why's the footage bad' is very ridiculous because not as many people have great cameras on their phones like they assume and without a proper lens, zooming into something 300 or so feet away is gonna look terrible and almost none of these videos are very close to whatever is being recorded.