Be kind to annoying people like our friends and family requires whole object relations. As we all know how different people can be and when the differences affect our own interests. Talking as someone who has nothing in common with most people.
On the other hand, throwing platitudes on total strangers requires minimal efforts, while offers positive exposure for our image management.
Some people can only be kind or offer “empathy” to strangers because they simply don’t have the capacity to do otherwise.