Part of the normal preventive maintenance of vehicle is body component lubrication. This typically comprises of your door, hood, and trunk/hatch hinges as well lock cylinders. Your owner's manual will specify the lubrication locations and frequencies as well as the recommended lubricant(s). Typically, this lubrication is done at the same time as the engine oil is changed.
Many people will take their vehicles to a shop to have this preventative maintenance done for them. It is important that the vehicle owner become familiar with the maintenance schedule of his vehicle and understand what is required at each service interval and especially at the oil change intervals. Often, when people shop on price alone, a cut-rate shop only does the minimum work possible with the cheapest labour and materials, with the eye towards upselling extra work.
Hinge lubrication is extra work and there is no way for the shop to charge the vehicle owner for additional parts and labour to install worn parts (unless it's also a body shop). Unused doors can become seized from corrosion. Driver's doors can suffer from worn pins & bushings resulting in hard-to-close sagging doors. If you hear the door making a creak or groan when you open & close it or if it takes some effort to open & close your door, your door needs lubrication.
The following video shows the work involved to replace the pins and bushings in a door. In this particular vehicle, this work is relatively easy. Replacing the worn parts in other vehicles could involve removing the doors and/or replacing both upper and lower hinges.
To avoid this unnecessary grief, keep your door hinges lubricated.