From Emunah v”Bitachon by the Chazon Ish (Rav Avraham Karelitz z”tl):
The words of R. Yisrael Salanter on this matter in his letter* are very pertinent: In prohibitions of unkosher meat, in mixtures of meat and milk, man is rules by habit: he naturally recoils from the forbidden, and is not overwhelmed by his evil inclination. On the other hand, in matters between man and man, he sins blithely and has no fear. Even when his fellow-Jew sues him, he finds ways to avoid both him and the trial. But the prohibition of robbery is more severe than the prohibition of eating non-Kosher meat, for when it comes to robbery, even Yom Kippur does not provide atonement, and as long as the object is not his according to the law, he is guilty of robbery. But since there is no regular habit of observing this law, his soul has not acquired love and fear of it.
*A pdf of Rav Yisrael Lipkin of Salant’s Iggeres HaMussar is available here.