Normally these types of indifferences are inadmissible.
One issue you mentioned in your question can't be solved by a single person alone if he has no power to do that. Did you notice that?
Is it "OK" for a person to stand by while another is harassed or
assaulted?
Most people don't interfere in the quarrel among drunkards.
When a person has a great aim to accomplish in his life (e.g. to save the lives of so many people), sometimes he will ignore some issues.
Sometimes the harassment may be the reaction of an action.
The person may not be willing to react due to his bad condition (e.g.: very weak due to some illness).
Sometimes, if the person responsible to solve the problem is there we usually do not react quickly.
Is it "OK" for a person to have multiple homes and others homeless?
Is it "OK" for a person to have access to thousands of tons of food
for years and another starves?
The persons who destroy the homes, food etc without allowing anybody to use it, are certainly traitors.
Is it "OK" for a person to have unlimited leisure and another an
indentured slave?
The authority to stop such issues are also responsible for these. Then whose behavior would you blame/name first?
Here we can see at least three persons:
- the person who is responsible to stop such activity
- the person who enjoys unlimited leisure
- the indentured slave
But we usually consider two persons only and name his/her behavior.
When there are more than two persons and when the reference also changes, the name of his/her behavior also changes.
You may try to name the 2nd person's behavior more precisely without considering the 1st person and considering the 1st person. Are they the same?
[This test is applicable also to the two questions given above.]
Is there any word for this type of behavior?
Here a one-word won't suit everywhere. We need to name such behavior according to the situations.
The persons in your questions may be rude, introverted, selfish, thoughtless, inconsiderate, domineering etc.
The following link may help you to clear one of your doubts. Sometimes you can connect it to other doubts also.
http://www.holy-bhagavad-gita.org/chapter/3/verse/35
[You are searching for a suitable word. This site deals/analyzes ideas very deeply. So I don't think this site can suggest a suitable word considering different situations. IMHO you should migrate to a suitable site.]