German Ministry of Education Throws Away PCs For 190,000 € Due To Infection

Well, there are many reasons. For once, it might not be legal for companies to take apart and dispose of their own computers without a permit (for safety and pollution concerns). Those permits and regulations might also raise the costs of the recycling company, which may need special equipment or training for its employees. Then there's labor costs, which in Germany are well above the EU-27 average.

The issue was mostly the CRT's - they're like 20 or 25 kg each, I would've had to lug all of them down 3 flights of stairs, plus I would've had to hire a van to bring them away or drive 5 times or so with my car. Plus there are hardly any metals in the monitors, so I wouldn't have gotten paid for them anyway. We were moving offices at the time, I had other things on my mind. I made a deal where everything including the CRT's and a bunch of really old stuff like old ink-jet printers etc. were taken away. Maybe I would've gotten paid a bit had I sold just the PC's - even then it would've been so little that it wouldn't have been worth my time, plus I would've had to pay more for the rest.

Regardless of whether it's possible to get some pocket change for old pc's, the point is: it's not cost effective, when you count the hourly salary of a professional, to do anything more than the absolute minimum to dispose of old computers. Especially for a government organization - bureaucracies are not designed for cost-effectiveness, but for predictability and accountability. That is not a value judgement, just an observation, but one that immediately dispels of 50% of whining about 'governments wasting money'.

The size of the error resistance coding you'll need will quickly dominate the size of your data. Also the argument is a probabilistic one. It's not that certain data will be recoverable, only that there may be a non-zero probability that some data may be recoverable.

If you are able to get at the entire physical media then a certain combination of high and low bit writing is necessary or one can read some previous bits with specialized hardware. There is a DoD standard for writing enough combinations.

But with modern drives you are not getting at the physical layout. The drive may detect an error and remap surrounding data for you. Consequently, some data surrounding some badblock(s) in the past will potentially never be overwritten by your process. Someone with separate hardware or an alternate firmware could always retrieve it.