I think that even in practice being able to determine the Kolmogorov complexity exactly is very decidedly not the usual case; you need to know that every progra

I think that even in practice being able to determine the Kolmogorov complexity exactly is very decidedly not the usual case; you need to know that every program shorter than your candidate fails to do the right thing. Your general point is very much correct, though. A clearer-cut application: In general, one cannot prove that a program does what it's supposed to; but if doing that is important, "all" you have to do is write it in a way that makes a correctness proof possible.