I am as white as can be - of British/Northern European decent. Because of that, I have never felt discriminated against in any way.
I have felt uncomfortable talking about race with others, but it's usually because I'm trying to make them see that there is not inherent difference between ourselves and POC.
None of the experiences really surprised me, as I have talked with my friends who are in a lot of these various groups about how they are perceived and how people react around them.
For the last one, where the one young man talked about people changing the side of the street or clutching their purses tighter, it makes me wonder if I've ever done anything like that without thinking. OR, if when I look at them, if they think I'm judging them for their colour, and what is the "polite" amount of time - am I staring? Am I making them uncomfortable? It's a hard thing to know.