And why does President Joe Biden (D) not want us to know?

The Secret Service says it does not keep records on who President Biden meets at his residences in Delaware, which he frequently visits during weekends and holidays.

Never mind that

During his inaugural year in office, the president spent about one-quarter of his time at his residences in suburban Wilmington and Rehoboth Beach, during which time he took personal time and conducted official business.

At best, this is a violation of the spirit of the law requiring the President to keep logs of his visitors, his meetings, and the duration and content of them.