Banks have been under siege in recent weeks for widespread corner-cutting in the rush to process delinquent mortgages. The accusations have stirred outrage and set off investigations by attorneys general across the country, prompting several leading banks to temporarily cease foreclosures.

But lawyers who defend consumers in debt-collection cases say the banks did not invent the headless, assembly-line approach to financial paperwork. Debt buyers, they say, have been doing it for years.