I was waiting for somebody to mention the "big brother knows everything" conspiracy.
Is it really that hard to understand the limitations of today's technology? Recording the entire surface of the Earth through satellite images with enough detail to be able to distinguish something the size of a small shed, let alone debris from a wreck, at any given instance is impossible. You're either capable of high quality shots covering smaller areas of the world, or you have large shots that are too distant to distinguish anything other than cities.
Second, even if it was possible to record the entire planet in detail in real time, the storage capacity necessary to hold the data is just not plausible. It would require a massive facility beyond anything currently built to store a day of footage. The U.S. government only takes hourly shots in localized areas for this very reason. It's just not plausible to record on that massive a scale.
Lastly, even if we did have the means to record and store the data, that still would require manually locating the plane, as our current technology has trouble differentiating letters and symbols from gibberish, let alone a specific nondescript clump of pixels located within a huge mass of nondescript clumps of pixels. Using previous flight information would save time, but it's still a time consuming process. Considering our actual limitations on technology, even if we did have a shot of the crash, it would be very, very hard to find it because of the sheer size of the ocean in relationship to the plane.
And do you even know how you locate somebody using a cellphone? It's done by using triangulation. The cellphones signal would have to relay to 3 separate sources, while somebody is actively looking for the cellphone, and then using that signal to locate the cellphone based on signal strength between the 3 locations. It doesn't work if you can't get 3 sources to pick up on your signal, and if you go looking for it retroactively. And this is even assuming the cellphone is on. This was a flight, and you're supposed to turn off your phone during flights.
More importantly, why are these conspiracies still a thing? Every government involved in the search has made it clear they believe the plane has crashed in the Indian Ocean. Sometimes, everybody agreeing is a sign that it's probably right, not that it's a cover up or conspiracy.