There are many reasons why dogs like people to pet their heads. One of the reasons is that petting the head can make the dog feel safe and warm. This is an intimate expression that allows the dog to feel the owner's care. In addition, head petting can help dogs relax and make them more receptive to their owners' commands.
The dog's head structure is similar to that of humans. The scalp is close to the skull and is mostly composed of muscle and fascia fibrous tissue. These tissues are actually a very active area on the back of the entire body. Many methods and techniques can be used to relax and relieve discomfort in this area, such as head and neck discomfort, scalp tightness and numbness, dizziness, etc. This is also why cats and dogs like to be scratched and rubbed behind their ears. Relaxing these muscles and fascia can release their fatigue.
If a dog trusts its owner and treats the owner as a leader, then the owner will pat its head and feel encouraged and praised, and the dog will be very happy.