Why No Definitively and Definitely Provable, as Opposed to Speculative and Unproven, Alien Species Visitors to Earth or Observation of Other Worlds with Them by Our Space Sci-tech

Why No Definitively and Definitely Provable, as Opposed to Speculative and Unproven, Alien Species Visitors to Earth or Observation of Other Worlds with Them by Our Space Sci-tech

One big general reason, among other significant reasons, aliens exospecies that might exist, or really most probably do exist prodigiously, have not provably visited our planet and are not observable to the astronomy and astrophysics of our species is the host of reasons as to why our Earth-based native and evolved sci-tech incipiently advanced societies (since the late 1400s CE but most especially since the era of the onset of the industrial revolution in the late 1700s CE in Europe and Benjamin Franklin of the USA and his electricity experiment of that era) of the human species have not as human organisms visited, except for a few astronauts who briefly touched down and bounced around, momentarily, on Earth's moon, the other worlds and otherwise celestial bodies of our own stellar-planetary [solar] system as well as those of interstellar space and the other celestial systems of the universe: Firstly, many alien-world technological species, such as at the tribal level through post-primitive feuding and imperial polities or societies level, are as yet incapable of doing so (in which our and their space sciences and technologies at best are still insufficient and too primitive and do not measure up to meeting the task) and are biologically incompatible with and not adaptable to, other than through difficult, slow, Herculean and expensive measures, the great majority of even local solar-system other worlds; and, secondly, ancient highly or super cognitively and sci-tech advanced ETI (extraterrestrial intelligent) societies or civilization, naturally, by virtue of their super intelligence and social and sci-tech knowledge, knowhow and achievement as species and societies or civilizations, would tend to be utopian unto themselves, and often between and among themselves, for non-predator such ETI species, and would have the discretion to choose from among billions and trillions of alien worlds, near to far, those choiciest to them for contact, colonization and development, and relations and those for non-contact and non-relations.  Also, the tier of the most advanced super cognitively and technologically ETI exospecies would highly likely possess invisibility sci-tech knowhow and would be able to invisibly, both with their biological bodies and their space-travel vehicles or other means, visit other worlds, within the space-travel reach of their biological lifespans or prime-of-life period of them, whose technologically or sci-tech smartest inhabitants are much less sci-tech achieved as theirs, such as our comparatively sci-tech infancy-stage human species.