Yes, you observe rightly. We all serve customers. The employee's customer is the employer.

A friend told me he thought it would be great to work as an independent (like me), so that he could be his own boss. I smiled and told him it is just the opposite; the consultant serves many bosses--one or more for each client.
This creates stress when there are conflicting time demands, and you must sacrifice ohter parts of your life to make time to please your clients.