If someone across the street much less halfway across the globe asked you to donate $100 to their cause you wouldn't until you had done some checks and balances.
Apples and oranges. Across the street you can "check and balance" in person. Not feasible halfway across the world, not for $100 anyway. And most of the information provided remotely (pictures, receipts, spreadsheets) can be faked. So it comes down to trust.