Simple- Laptop Hard Drives - they are manufactured using a set of thin GLASS plates coated with a super-thin sheet of steel on either side, providing the magnetic element.
However, unlike the Aluminum used in desktop hard drives, glass is not magnetically dead... so data corruption can occur MUCH more easily. Plus, the drives are HIGHLY susceptible to vibration, which occurs whenever you pick the laptop up while it is still powered on.
True. And they still use discrete components on motherboards and in power supplies - and those things come in varying degrees of reliability. My youngest son is an IT service tech and he's told me they've seen a rash of component problems in the past year - mostly related to capacitor failures (leaking, shorted, etc.).