You fix the system not because of the cost today but because the cost it will eventually cause.

Poor record keeping and bad policies about data validation tied to sending money to people if not today will eventually result in massive fraud.

Furthermore the notion you put forth is trash lazy thinking. Cost or no cost you do things the right way. But I don’t even buy you can calculate the cost of doing it wrong correctly to even have a sound conjecture that fixing it is more costly.

Your point is also covered in the audit report linked by the parent.

Cost was not the only factor. They seem to be trying to handle missing data the right way rather than use a kludge.

They did not want to add inaccurate death data to Numident records, for a variety of reasons, one being that it could cause release of information for living people when they're accidentally added to dead people records. The SSA also thought adding annotations would legally require a new regulation and would have impacts on other consumers of the data (ie. states, etc).

How to handle missing death data in this case does not appear to have a clear and simple solution. But it also does not appear to be evidence of poor record keeping for modern records or a major cause of concern for "eventual massive fraud".

But what if the right way is judging the pros and cons of perfection and doing what makes the most sense?