Why has NASA has never just put a $20 microscope attached to a web cam on a mars lander and designed a dirt conveyor belt to continually look at dirt for actual moving or fossilized microbes?

Have you ever wondered why instead of all the roundabpout methods of finding indications of life that NASA has never just put a $20 microscope attached to a web cam on a lander and designed a dirt conveyor belt to continuously look at dirt for actual moving or fossilized microbes?

Why are they always doing more expensive indirect "searches" when a simple video of a microscope looking at things in the soil would do a far better job of determining whether or not there is or ever were life on Mars and far more reliably and cheaply?

If a scientist wants to see if your blood,or a pond or dirt has microbes in it like dangerous amoebas do they do indirect tests or do they simply LOOK THROUGH A MICROSCOPE.

Why do you think that is and why hasn't it been done on Mars?

BTW a friend of mine had direct email back and forth communication with several of the mars lander designers at JPL trying to encourage them to put microphones on the lander as well as a microscopic lens. They even said they brought up the ideas at their design meetings. I saw the emails myself.

Neither happened. They did however put a magnifying lens on it that is specifically too low a power to resolve any microscopic life if it exists in the soil.

Ask yourself why if they are putting a magnifying lens on it to magnify would they choose to put one on that will not resolve the microscopic life everyone is always talking about trying to find?