The real world is full of anomalies and missing data, the system deals with it according to the law and administrative precedent.
Edit: here you go: https://www.ssa.gov/help/iClaim_poa.html
When dealing with a population the size of the USA, and edge case you can imagine will be hit. Dealing with uncertainty is a must.
In my country such cases get an unknown date of birth. Having just a year of birth is also possible.
Many service members during the drafts would add or subtract a few years with the help of local authorities.
My grandfather didn't know his birth year and lied to make himself seem younger when it suited him.
I have great-grandparents without any documentation that we suspect were fleeing wars or had been shanghaied
I have at least one 3x great-grandparent with only a first name before her marriage. We know nothing else about her.
There have been a lot of threads of 'Things Programmers Believe About Time' that are worth looking into. The exceptions to 'computer time' and reality are fun and tough to deal with. Same things apply to names. Suffice to say, Elon's crack team hasn't really thought of the reality of life and the messiness of it.
But that's not the point and we all know it.
Think of the United States during the Great Depression, for instance. Today’s 80 to 100 year olds were born in that era.
Do we know those people are actually receiving support? Could be a hack of the system to take people out of welfare, without removing their whole entry. Maybe those are (again) double-entries with a different purpose, or dead people, or future receivers, or old entries, or just poor data. Just looking at a database, without looking at the business-logic, is usually not a good argument. Heck, It would be actually funny if the DOB of those entries is just saved in a different table or field, and they just did not understand what they are looking at.
This entire tangent is based off Elon Musk not understanding COBOL or the thing he's looking at before he started ranting on X.
There's literally not enough information about anything, it's just anything which can be spun to fit the narrative he's already determined.
What would invalidate the benefits is death. This 150 year old business is a corner case obviously, so finding those dead people is not so easy. I'd assume there are more checks issued to dead people who were never reported than dead people who were properly recorded as dead. I don't know the frequency of fraud in either case but one is easier to get away with than the other.