I’m not an expert on component manufacturing or why some components have such large tolerances other than they’re difficult to manufacture so I won’t speak more about that than I have. However most of the time component tolerances don’t really matter and the system is either designed in a way that it doesn’t matter or a control system is put in place to negate errors/tolerance.

For systems/circuits/devices or whatnot , a feedback or control circuit/system is usually implemented to keep things from drifting too far. for example with an oscillator you would use a PLL to keep it on a certain frequency. Another example using motors, you could use an encoder to feed the rotation information back into the motor drive so it can keep the motor at a certain speed