אִם־יֶחֱטָ֨א אִ֤ישׁ לְאִישׁ֙ וּפִֽלְל֣וֹ אֱלֹהִ֔ים וְאִ֤ם לַֽיהוָה֙ יֶֽחֱטָא־אִ֔ישׁ מִ֖י יִתְפַּלֶּל־ל֑וֹ וְלֹ֤א יִשְׁמְעוּ֙ לְק֣וֹל אֲבִיהֶ֔ם כִּֽי־חָפֵ֥ץ יְהוָ֖ה לַהֲמִיתָֽם׃
Si un homme offense un autre homme, le juge en fait justice; mais si c’est Dieu lui-même qu’il offense, qui intercédera pour lui?..." Mais ils n’écoutaient point leur père; aussi Dieu résolut de les faire mourir.
Akeidat Yitzchak
The reason that sins committed between different human beings are not subject to atonement of Yom Kippur is, that any sin in which man's body is the major party, can only be atoned for by that same body making the appropriate restitution. When reconciling oneself with one's fellow man, it is the senior person, the scholar, who must make the first move, just as Abraham had done with his nephew Lot. (Genesis chapter 13)