Non-programmers can understand technical things but they do not have the thing that is so hard even for us - technical judgement. They do understand how technology works, but they cannot understand why a certain approach would take three months and another one three days. (After all, programmers are anecdotally horrible at this kind of estimation as well.) This represents a great opportunity to synergize with them.

With your team, the basic assumptions and goals do not need to be restated often, and most conversation focuses on the details. With outsiders, it must be the other way around. They may not understand things you take for granted. Since you take them for granted and don't repeat them, you can leave a conversation with an outsider thinking that you understand each other when really there is a large misunderstanding. You should assume that you will miscommunicate and watch carefully to find this miscommunication. Try to get them to summarize or paraphrase what you are saying to make sure they understand. If you have the opportunity to meet with them often, spend a little bit of time asking if you are communicating effectively, and how you can do it better. If there is a problem in communication, seek to alter your own practices before becoming frustrated with theirs.