This observation calls for two actions:
1. Build time (directly or indirectly) into your project to educate your clients and customers on the discipline of software engineering and software architecture. You'll have to spend time convincing them that a disciplined approach to creating software is not a choice, but the way of life.
2. Create a mini curriculum, or at least talking points, ahead of your engagements with clients and customers. You need to be proactive in your education sessions and they always should be done in the context of a specific business problem or a solution you're working on.
If a client or a customer has real world experience with enterprise grade software development or implementation you must gauge past experience. On a positive side a client may be receptive to your disciplined approach. On a negative side, if a client had negative experience, you need to understand client's perception of the software development process and demonstrate how your approach is better.
And most importantly - pay attention to the right approach. Selection of agile or highly structured software development processes and degree of requirements elicitation and software architecture analysis differs from problem to problem. Understand your client's situation and explain why your approach makes sense in a given situation.