For several years, my wife and I volunteered at a Hospice for the terminally ill. I was late to get to work there one morning, and took the toll road ... but did not have any small change (I think it was 25 cents), and only a large $20 bill. The woman in the toll both could not take the large bill, refused to accept my promise to pay double on the return trip, gave me a hard time, filling out forms and blocking traffic too. I got a bit hot under the collar and told her off a bit. Jerk!
Not two hours later, I run into the same woman, crying next to her dying mother's bed in the hospice
... True story.
Everyone's life has many causes and conditions that brought them to that place. The fellow who cuts you off in traffic may be worried about losing his job, or the rude sales clerk may just be having a bad day. I try to keep that in mind now.