With the density and sophistication of controllers, the odds of what you describe are pretty long in this day and age. Don't you think?
Not really. Drives are designed to be cheap. This means they are designed so that data will be written as accurately as necessary to ensure sufficient read margins. There's no benefit to being more precise than that, so drives generally aren't.
That being said, writing random data repeatedly makes it difficult to distinguish which bits of magnatism were the random overwrites and which bits were there before.
...odds of what you describe are pretty long in this day and age. Don't you think?
Then again, maybe the good guys might get lucky. E.g., the incriminating data is written when the drive is at its normal operating temperature. Then, when the political temperature starts to rise, panicky crooks sneak in in the wee hours of the morning and power on a cold computer and immediately run the wipe utility.
In that case, the erasure bits might not fully cover up the original data. Then, if you took the drive out of the computer, you might be able to manipulate its control electronics to ease the read head directly over what's left of the original data and possibly recover it.
Similar results might be possible if the evidence was written on a new drive, but the erasure was done after the drive had aged while in service.