OK, It's awesome for your son to be playing blockland, but trust, is asking to much... You see, trust gives them access to do anything with the persons bricks. Making bricks is a hard thing to do, so, they don't want people deleting it, messing with it, putting stuff on it, and planting bricks on it.
So, tell your son, If you want trust, help the guy out, and if the person needs some help on the bricks, make some bricks that gives some extra time for the person.
+Same as Admin, and Super Admin, you have to be close to the person, then he/she'll give you TRUST, Admin, or Super Admin.