Also, proper disposal requires either time, money, or both. A bankrupt company doesn't have money. It may have time, assuming people are going to stick around, but chances are their shredder has been seized by creditors. People are not going to stick around to shred things by hand, literally.
Aren't there any laws regulating this? Apparently, such issues are covered by FACTA, the Fair and Accurate Credit Transactions Act, and although its guidelines require that "businesses to dispose of sensitive financial documents in a way that protects against 'unauthorized access to or use of the information'" [msnbc.com], it stops short of requiring the physical destruction of data. I'm not a lawyer, but perhaps there's enough leeway in the language for one to go around dropping sensitive documents in dumpsters?