Crime novel trope: special passphrase deletes all data

[LSLGuy]

Here’s the last thread on point with some excellent refs to real experts debunking of this UL:

How do they 'recover data'?

I see and hear ads for companies that recover data from dead hard drives. How is this done? What do they have that the rest of us don’t? Are their secret/expensive programs not available to the general public? Or do they actually open the hard drive and do something to the innards with special equipment?