The best example I can think of the external environment impacting on customer service is in the service industry.
The atmosphere, ambiance, branding and every customer-facing aspect of the business gives a customer an idea of what kind of service to expect.
So too does the price point at which a business enters the market.
For example, compare the external environment of a very expensive restaurant to a local taverna.
While both may be perfectly enjoyable locations in which to unwind, the visual and environmental cues trigger expectations of a different kind of service.
Interestingly, it doesn't necessarily mean that customers expect to be treated better.
For example, a customer dining in a fine dine environment is less likely to kick up a scene over displeasure over the customer service as opposed to a more affordable dining experience, where complaints are frequent and more vocal.
On the flipside, a fine dining environment would be expected to go to great lengths to keep customers happy. The same can't always be said of environments that don't have such finesse.