Trust is the underpinning of almost any human relationship, personal or professional. It’s hard to run deep with someone -- develop their career, marry them, etc. -- if trust is lacking.
One of the biggest concerns people tend to have with outsourcing a function, especially a function as crucial as software development, is “How do I know I can trust the team I’m giving this work to? How can I trust them if I don’t see them every day in my HQ offices?”