Reddit and Tumblr:- solved the problem of sharing links within communities pseudonymously
Tinder:- scaled hookups
Substack:- enabled writers to monetize their periodical content
Twitter:- enabled people to broadcast extremely concise messages globally
Letterboxed:- enabled people to share their film prefs (not sure if this is a real problem, and I actually had to Google this one)
Start by going around and asking businesses near you what the biggest issues are that they face. Sometimes a solved problem in the US may not be a solved problem in another place. Or sometimes a new business trend will open up doors to disrupt traditional businesses. But it all roots back to the problem - if you're not solving a real problem, you're not going to be successful getting even 1 user/customer.
Potential minor problems I would want solved: 1. When I have very interesting discussions with someone I wish I had it recorded so I could post/share it online. I am thinking just daily stuff without having to sit in a room together and do a podcast. This can KINDA be solved by livestreaming nonstop but that's far from ideal and does not have mass appeal.
2. A more modern way of finding jobs - I really believe there's a lot of improvements to be made here esp in Denmark. We use Jobindex, LinkedIn and Jobteaser primarily and all services seem ineffective. Probably just a university student problem. Regardless, it does not sound like an interesting problem to solve like the other ones I mentioned above.
3. Speeddating. I don't struggle with going on dates or picking up girls IRL but it would be more fun if you could just click "QUEUE" on your phone and it automatically sets up a blind date - maybe this actually exists already? Sounds so fun.
On your ideas, I would remark that job hunting and online dating are both still very underserved problems, and as you mentioned, vastly inefficient. Dating is an interesting scenario - OkCupid was actually doing very well at solving the problem with a high success rate, before they started regressing their algorithm after their acquisition by Match.com. On the other hand, job hunting will always remain an elusive problem.