It's all about liability and shifting responsibility.
If failure of a component could, on its own, lead to a safety hazard, then any system which incorporates that component should be designed to fail safe. For example, if a microcontroller responsible for controlling a critical system locks up, the design might include a watchdog to reboot it, and should in any event end up in a safe condition if the reboot is unsuccessful.
For something like a household appliance, the applicable safety standard implies the need to consider 'what if?' each component were to fail in the worst possible way. Certain design features may be required, such as physical isolation between the mains and any part which can be touched, so that even if a whole bunch of components were to fail short circuit, the fault would still not be able to electrocute anyone or start a fire.
If you need greater reliability in any individual component, then suppliers might be able to provide it - but the price will go up dramatically, depending on the amount of testing, certification, and (especially) liability that tha supplier is expected to provide or accept.