I'm not going to drive a disabled person to the train station
Why won't you drive this person?
I want to help, but I don't have time.
You should always help out people in need. If they have a disability, you should be there for them.
But I just told you I don't have time and I'm not obligated to help.
That's true, you aren't obligated to drive anyone anywhere if you don't have the time.