Obvious, if otherwise insignificant signs of rule bending lead to more frequent, more serious rule breaking.
The “broken windows” theory of policing says that obvious signs that rules are optional, even somewhat trivial rules, lead to a snowball effect of lawlessness. The crackdown on these small but obvious cues in similarly obvious ways can have a disproportionate effect on the outcomes elsewhere. This was credited for the dramatic reduction in crime in New York City in the 90’s, after the subway graffiti was cleaned up and an example was made of people skipping fares. Public displays of zero tolerance preempt bad behavior.
This can be applied at the personal level for upholding your values. Fight at the margins and you’ll never have to fight at the core.