I agree with your comment, but this one sentence is sadly not true. Until last summer, Seagate Recovery Services (formerly ActionFront) was a division of the company I work at. Their Canadian lab is still collocated with us. A disk drive I took to them was completely unrecoverable (the head was scraping the platters). Now, partially because I work in the dats protection industry, I had another copy of the data. The point remains that the drive in question is unrecoverable.
I'm also aware of, but have no details on, a customer lawsuit that relates to the customers' missing data where the customer misconfigured their backup. Significant chunks of that data are apparently gone forever, too.
Of course, if the magnetic field is gone then it's certainly possible for it to be truly unrecoverable, but that bar is very very high.
One firm, DriveSavers (which incidentally is who Apple sends all their data recovery problems to), has an ISO-5 cleanroom and maintains a hall-of-fame of ridiculous situations they've successfully recovered: http://www.drivesaversdatarecovery.com/company-info/museum-o...
Let's imagine that this purely hypothetical university had a user who accidentally blew away some data. From the perspective of the sysadmin, thtr data is unrecoverable. But data is never really unrecoverable. Data is like oil: if you have enough money, we can drill arbitrarily deep for it.
Let's pretend that the undelete feature would have cost our hypothetical university X. "Drill as deep as you need" might get quoted at 100X or more. And that is totally reasonable, based on the hypothetical costs and benefits of the hypothetical data recovery.