Honestly? Some people. I'm not saying LW was right, here, but it is very common to invite a few people who are more friends of the parents than the couple being married. It's less common now that more couples are doing most of the wedding work and payment themselves, but we had a tiny wedding and still invited a couple of people who were more friends of my in-laws than my then fiance.

The LW says they've been neighbors and close friends for 25 years. Unless the bride is in her 40's, the LW has likely spent time with her and even watched her grow up. I think she's making a mountain out of a molehill, but I can understand her maybe a moment's (a moment's) hurt.