People can think fundamentally different because their thought is a product of time, culture and tradition.
Where my Dad wants to live in a shared room when he is without family, as he did during his 6 months stint at Gurgaon, I, on the other hand, always want to live in a single room. It is easy to live in a single room because you have space that is yours to keep, design and trash, as you see fit. Other people invariably have their own preferences and over a period of time, the shared boundary of living together becomes bigger and bigger. As the shared boundary gets bigger, it is quite possible that disturbances, arguments and unnecessary quarrel may arise. These quarrels somewhat take away from the joy of living together and provide a stark but practical contrast to the shared experience.
It is not so much as wanting privacy as it is about wanting security. Your first job in any new living environment is to secure it from outside influence. Early human beings had to ensure that their tents and camps were secure so they would not be eaten in their sleep. We were still living in the dark wilds 10000 years ago and the jungle was full of animals and predators. Man was not the dominant species, that he now is.
Security implies creating a space where you do not feel hurt. Space where you can feel confident, calm, relaxed and free enough to express yourself without inhibitions. Hesitation is the enemy of mastery. And, any man or woman aiming at self-mastery needs to be able to express themselves without hesitation, inhibition, and disturbances.
The end goal of security is harmony.
In the state of total security of mind, harmony and global action is the result.