Its unclear if you are talking about yourself or making a general observation about people around you, but in case its the latter: I believe this to be very much subject to strong confirmation bias. You dont open up because you believe thats just not what people do. But I find that to be false 9/10 times I break through the fear and show genuine interest.

Safe spaces would include anywhere people that share a common interest gather, for me thats a climbing gym I go to regularly. Volunteering is also great in regards to meeting people that share similar values.