My answer rate (the amount of accepted answers) is rather important to me. Low rep users, especially the ones who come from stackoverflow, generally don't accept answers. This is my primary reason for ignoring questions from low rep users.
My second reason is that the questions just flat suck. I'm pretty knowledgeable in Powershell and Automation so I gravitate towards those kinds of questions. Most are lazy people wanting someone else to write a script for themlazy people wanting someone else to write a script for them. Others lack sufficient knowledge to understand the difference between a technical question and the need for troubleshooting. I've tried in the past to explain in depth how or why something worksexplain in depth how or why something works the way it does so the person might understand their question is unanswerablequestion is unanswerable. Those attempts generally end unfavorably. Even when a high rep user get's an in-depth answerhigh rep user get's an in-depth answer you're not guaranteed to find out whether your time was even worth itwhether your time was even worth it.
The last reason is those UIP's which Womble references. I'd like to assist the community more but my rep level isn't high enough. I asses each new question (and by extension its asker) to determine if it's something that can be answered, doesn't need a ton of troubleshooting effort to get to the real problem, and whether or not the asker accepts answers. Programmatic questions generally require deep effort on my part as I need to parse code, write new code, and test it before posting. All the while not knowing whether or not someone else is also answeringsomeone else is also answering.