The article says she died from her injuries some time later. So, she didn't die instantly on impact.

I know more than average about homelessness. A high percentage of homeless people have serious health problems. If she was homeless, she may have already been in very poor health. That may have contributed to her death.

I can think of potentially other contributing factors, but I am leery of coming across like I am badmouthing homeless people. They are subjected to enough hostility and prejudice and I am usually trying to advocate on their behalf.