I can't add much to H3rmit's reply. That's pretty much my view. I see as many considerate polite people in my store as the other type.
Maybe you could try being a bit less sensitive. Of the three example you gave only one was really offensive behavior. You weren't entitled to that last cart any more than the other woman who wanted it was. Later on in the store you may have been blocking someone with your cart. I doubt that those people were aware that they were blocking you. The aisles are narrow... this is just something that happens in a supermarket. Most of us are concentrating on getting our stuff rather than looking around to see if we are in someone's way.
Try to see the donut, not the hole