Most databases answer "here's what matched." They can't answer "and this is everything — nothing withheld." This page can: your browser fetches every public leaf and computes the answer itself, so the completeness proof doesn't depend on us.
Streams number their records 1, 2, 3… so a missing number is visible — silence becomes evidence. Independent version of this check: check_stream_v2 in log-server. A dense stream proves nothing was withheld; it never proves any record is true.