We're driving for a company who is under heightened media scrutiny and has a rabid anti-everything-Uber contingent on social media. If that lady had pulled out a phone and taken a picture of OP literally spilling her groceries onto the sidewalk, OP would have made prime time news, and gotten a ton of grief on social media.Sometimes it's better to get your 1 star and just move on.
Why? Always keep level headed. If you choose to deal with people for a job, you gotta know how to deal with people.