First, don't assume that internal customers aren't "paying", just because you may not see an exchange of money. Often companies WILL transfer money from an "internal customer's" budget to the department that serves them. You may not see that exchange, but it often occurs.
In some ways, internal customers ARE as important to you, and to your employer, although the reasons are a bit different than for paying, external customers.
Here are a few things to think about.
- Some departments actually do little else than serve internal customers. That's the job. For example, human resources departments, accounting, informational technology departments pretty much serve internally. If you aren't serving internal customer needs, you may find yourself out of a job through outsourcing, so that's one reason to pay special attention to those internals.
- Internal customers can make your life as miserable, or MORE miserable than external customers. In most industries, customers come in and out. You don't LIVE with them, and neither do they have the easier access that internal customers have. Further, internal customers can climb the hierarchical ladder to complain, much more easily than externals, and some will have a lot more clout. Do you really want to explain your inattention or lack of customer service to the executives?
- Generally speaking, companies that are efficient, and tend towards being positive places to work also serve internal customers well. Think of internal customers as the parts of your car engine that need to be maintained and attended to so the entire machine works. A broken fan belt can destroy the ability to use your vehicle. Poor customer service to internals can stop the organization cold.