As someone who is _often_ late, your inability to be there in time is not someone else's problem. Unfairly punished...gimme a break.
I try to be generous as much as is reasonable. I generally assume the person who cuts me off in traffic may have an urgent need, but vaulting every misdeed to an assumption that it's due to some unknown disability crosses into unreasonable territory, if for nothing else than it's probabilistically a bad assumption. Taken to the extreme, it becomes enabling for everyone who does not have a disability but gets away with bad behavior.