There must be some way to track planes to keep them from going missing??
Generally there is. There are actually a series of systems that will allow someone with proper access to track an aircraft. Newer post 2005-ish aircraft all have some sort of GPS transponder built into them. Usually the transponder service provider charges a fee to have it activated, and aspects of it can be disabled from the cockpit such as what they think may have happened to the first missing plane. There is also radar. in the US, we have a super dense radar pattern for aircraft control, weather monitoring and defense. Anything flying through the air above 100 feet off the ground and larger than a teacup will show up in some form on most of those. radar sites, with the occasional gaps in coverage behind mountains or in very sparsly populated areas of no strategic importance. You also have various surveilance satilites floating around that can see aircraft from orbit.
The problem is, that most of the rest of the world flies rebuilt 1980 era Boeing 727 or russian Aeroflot aircraft which don't even know what a transponder is. They also have minimal radar coverage because radar sites are expensive to build and maintain. And satilite footage is generally available in some form, but you have to know where you are looking to be able to know what picture frame to look at at what time period. Otherwise there are thousands of pictures to sort through, and the satilites are often moved around to view important strategic concerns and may not have been in the exact right place to track a 650mph aircraft flying evasive patterns at low altitude.
Even if you do have satilite or military radar feeds, there is a strong desire by most countries not to show their military sensor capability to the rest of the world.. Couple that with local ******* contest rivalries. areas of the world that the US really doesn't particularily care about, a situation where allowing China to fail to find an aircraft is seen as more politically desirable and useful than the U.S. expending major efforts to locate it, and a search being ran by a bunch of idiots out to throw influence around and save face after a coup rather than actually finding out what happened, and I'd be suprised if they ever find the aircraft. it had to have gone into the water mostly intact and sank without releasing debris to the surface otherwise something would have been spotted by now. That particular sea area is very deep, and covered with a very thick layer of iron rich sludge on the bottom too, so locating something from the surface or towed arrrays may not work.