People tend to not say sorry when they are wrong because of pride. Pride is the only reasonable cause of that. I mean, why shouldn't you say sorry? Even when you're aware that you're wrong? You must have an element of pride inside you to be that way.

Secondly, people who never accept their weakness tend to be apprehensive about saying sorry. It's more common with people who see themselves as 'the most upright'. They feel they are always right so they wouldn't say sorry went they go wrong.

I must say at this point that it is very wrong to have the mindset that 'saying sorry is needless'
Apologizing when you go wrong is the virtuous thing to do any time any day. When you Apologize for your mistakes, it enhances the relationship between you and the second party. It builds up the very bridges that lack of tendering apologies would destroy. And again, it is not just only about saying sorry. One has to make amendments after apologizing for his or her wrong deeds.