So imagine there was a way you could turn sensitive information, like passwords, into a format that was unreadable. To convert them back would be infeasible, since doing so would require a ridiculous amount of computing power. However it was easy to verify this stored information is valid.
These one-way functions, know as hash functions, are well known and documented (for example see https://tortoiseandharesoftware.com/one-way-hash-functions-and-data-privacy-compliance/) but due to the additional complexity and limited financial budgets [ie outsourcing] rarely implemented.
Still the EJ share holders were happy due to cost savings and have been duly rewarded. Even after the industry collapsed and now staff are being subsided by the future tax payers.
I've previously contracted to British Airways, who after outsourcing to TCS, appear to be struggling to just keep their services running. Then there is Boeing.