This is also an international forum, so someone from Western Canada, for example, who goes to Europe for the first time will see hundreds of birds they have never seen before. Other people with 17000 posts might like to look at the gallery or the butterfly forum because they can't get out for whatever reason or haven't birded before. Not everyone here has space or money for field guides either. As stated by others, this forum caters for all levels of ability, old school, modern birders who started late and use cameras as a tool for id purposes as well as a nice photo and beginners. The reasons are manyfold and sometimes particular to one person only. Live and let live. At the end of the day, if you think the person is stupid, don't help them, its your choice, just as its their choice to be lazy/need confirmation/testing the waters/whatever. I woudn't worry about the why, if you feel like helping do it, if not don't.