Why hasn't space technology discovered life forms on other planets?

We can only explore those in our own solar system for now. We can discover other planets from other stars, but we can't see them well enough to tell if they may be inhabited by a life form or not. We can't even tell that about the planets in our own solar system with just a telescope.

There is some evidence of life on both Venus and Mars.  If extraterrestrial intelligences had visited our planet in historical times, we would either be aware of it more or less universally or they would hide effectively from us.  Governments wouldn't be able to stop them from becoming widely known unless they chose not to be.

Stories about aliens visiting Earth are not hushed up. There are many many books and TV shows about UFOs and aliens. 

Why don't we see any physical evidence or proof of aliens? Because there is no evidence or proof.Why doesn't the US government tell us about aliens? Maybe they don't know any more about aliens than we do. Why don't aliens come out in the open? Maybe there are no aliens here on Earth. 

Your question shows a massive ignorance of these issues.

First of all, if an alien civilization had looked at our planet only 10 million years ago, which is a tiny fraction of the age of the Earth, they would have found NO sentient life, never mind any technological life here.

Besides the massive distances of space that separate solar systems, there's also what's called Deep Time. The Universe is 9 billions years OLDER than out Sun and Earth. There has been loads of time for life to come and go in billions of billions of places, and we have no way, and likely will never have any way, to find any evidence of any of that.

UFO stories here are universally nonsense and bullsh*t. Deal with it.

The X Files was BAD fiction.

You clearly have no concept of the differences between exploration on the surface of the Earth, and the exploration of space.

Stock markets? Connection?

Lives on other planets may posses different forms of lives on earth , since all lives here on earth come from the earth of  this very world itself, consist of liquid, hard substance and gas.

You know, I've been wondering the same thing.  There have been countless documentaries dealing with this topic and we can just speculate what the possibilities are.  Unfortunately, in the Astronomy and Space section, people want scientific evidence and anecdotal evidence from both average people and reputable famous people or even evidence of real videos and photos of UFOs aren't enough I guess.  I think one day when our technology gets so advanced, we won't be able to deny the truth anymore....it would just be so overwhelming.

Because there is a scarcity of places for life to thrive

But never say never as Extremophiles keep reminding us of

Absence of Proof is Not Proof of Absence ( The Fermi Paradox )

And check out the Drake Equation

All it needs is a Factor of more than 1

Other planets in our solar system are not in the "Goldilocks Zone" of correct temperatures on the surface.  Earth alone is.  Not likely life might arise elsewhere.  Maybe an ice covered moon or Ceres asteroid might have a salty ocean with primitive creatures?

Other solar systems are just too far away to be able to tell if life is out there.  At a Carl Sagan lecture in 1976, I asked if anyone might go between star systems.  He said no.  Only exchanging information by radio will be possible.  We have not found any radio messages yet, and no physical proof of "aliens" visiting from other planets yet either.  I am open to the idea.  Might have a bad result though.  If it is a very advanced form of life, first words we might hear from them-- "Break out the bug spray".  Would be all over for puny humans.

The conspiracy theorists keep pushing the idea that Area 51 or Wright Patterson hanger 18 is full of alien ships, bodies, and survivors of crashes long ago.  Even ideas that Russians are hiding something.  Not able to prove any of that.  Stories get exaggerated to ridiculousness.

Bcoz humans are not so intelligent as you think they are plain dumbos especially the scientists saying aliens may exist.