It seems that many, many people avoid looking at their own foibles and dealing with them by focusing the bulk of their time on what’s wrong with others and then advising them what to do — uninvited. This is both sad and annoying.
I also agree that it’s easier/simpler to go with your expectations rather than to open your mind and heart to see what might actually be going on or what someone might actually be like. I’m sure I do that myself from time to time, although I try hard not to.