It's easy to have a high trust culture in a small org.
It's not hard!
"We're very proud of the high trust culture in our 15 person team. I don't know why larger companies can't do it, too!"
If you're a 15 person team and you don't have high trust, you're doing something very wrong.
The difficulty of creating a high-trust organization scales super-linearly with the number of members.