If they’re applying for a visa or citizenship there’s likely requirements that you must have spent X% per year in the country and not abroad, even if it’s inside the schengen zone (or similar). Asking for the exact dates of your travel outside the country is likely the best way to do that
There’s a threshold, you need to have been physically present in the US for 50% of the days of the year requirements.
For example if you’re applying for citizenship based on the 5 year rule, then you must’ve been physically present for at least 30 months (913 days to be exact) in those 5 years prior to your application.
18 months (548 days) if you’re applying based on the 3 year rule as a spouse of a US citizen.
So 8 days instead of 12 can mean it’s no big deal or it can mean you’re not eligible if those 4 days make or break your required amount of days physically present in the US.
It’s one of those silly things the government already knows but wants you report anyways.
While the US doesn’t do a passport check before leaving via the airport, airlines automatically send over departure information to CBP, that’s how they are able to show this information in the I-94 on the website.
Obviously entry is also recorded.
I suppose it’s a way to make it easier to filter out ineligible people at the beginning of processing applications without having to delve into the records to verify and in part to see if you’re honest.
