Mod-80, shindy didn’t say a car door, just a door. It could be a door to a store.
As for the story with reflectors, I don’t get it. That issue can really be pikuach nefesh. I’d think it’s more of a reason to help than the stroller situation.
Years ago, I was walking home from yeshiva and an old woman asked me to help her cross the street, by holding her arm. I was a 14 year old 9th grader at the time. I told her that I’d be happy to walk alongside her, but couldn’t hold onto her. She said thanks anyway, and asked someone else. I was later told by a Rebbe that there was no problem with me holding onto her arm to help her across.