ASK THEM TO SHARE THEIR PROBLEMS...

Don't overthink it. When you find people who ask questions on Quora or Clarity or LinkedIn (or a zillion other social media platforms) respond to those people that "if you want someone to start working on solving that problem, tell us what you want...". Then point them to ASTU. Cool?

Hey Shrikar,
Luckily, this question has a simple answer and it's two pronged. You've probably heard of User Research. In User Research we use 2 things to uncover peoples' pain points.
- 1. SHADOWING; following participants over a period of time and recording observations. It's a free-flow method and the researcher can probe where he/she feels they need more information. These session usually take between an hour to a full day and vary based on the complexity of the app and the research goals. The data collected is usually super reliable.
- 2. USER INTERVIEWS; this is basically conducting one-on-one question answer sessions whether directed or not is upto the needs of the projects, goals and context of user. So far I've conducted, Field Interviews, Phone Interviews, Skype Interviews, Street Interviews and done hundreds of hours in recordings. The data is usually very good especially for directed interviews. But the interview questions must be tried and tested but more importantly, designed for the target audience.
I am more than willing to introduce and coach you on the lean and "mean" variations of the two methods that uncover awesome insights.
Looking forward to hearing from you.

I think you should first determine some area to help people focus on specific subject. If you ask people what are your problems ? Most of them won't be able to answer you.

If you propose some context, it easier for people to provide feedback. For example, you could ask, is there something that bothers you all the time in the metro? If yes, tell us more about it. If no, is there another place where something particular is bothering you?

One way of determining those situation and target groups of people would be to crawl forums/groups where there are tons of people complaining about their problems. List those issues and try to get more feedback from those people ! This is how Airbnb got started by the way...