Is it true that (in time) OVER TIME/AS TIME PASSES it is harder to find people whom you can trust?
Yes, it is, but it is not because you are meeting more dishonest people (dishonest people were always there) it is because you have developed the ability to recognize dishonesty, and you have set a high standard and are more willing to disqualify dishonest people from being your friend.
People should earn your trust and when you see, once or twice, that they are dishonest, then they are probably actually dishonest.
Acording to philosophy and psychology, we tend to misunderstand each other since we have our own perspectives even in the same country and culture. In my point of opinion, even the launguage, both native and the second, is insufficient to understand each other. The launguage is just a tool to communicate "Images" in our brains, and the tool has error since we have to encode our images to words and decode the words to images. That will make a barrier against trusting each other.
So let's talk about "How to learn to trust". From my point of view, you might think "Trust" is a "Passive" reaction, but the truth is an "Active" action. We decide who trust. We have responsibility to do that.
I know it is hard, may be painful as well. However, if we think so, we will get power by the fact that we can choose who trust; we are not obliged to trust someone.
So my answer to "How to learn to trust" is "Trust yourself first". We have power and responsibility to trust. We can decide and develop ourselves. There will be someone who hurt you. It is what it is. It does not mean you are worthless. He hurts you since he may misunderstand you, or just for his purpose. Just that.
Thank you for reading. I apologise for such a long sentence. It was made longer since I also have had the same truble. I hope my images reach you clearly and it is helpful for you.