Willpower and capacity to deal with stress are limited resources, and you can run out of them. So why waste precious units of stress on small things that could be passed over?
Some small things are worth the stress, like looking both ways before pulling out. But disputing a ten cent charge at the big box store and making a scene, maybe not so much.
In most instances, low-level things of small importance should dictate that level of response — big energy for big things.