Nobody did anything wrong...
Besides...
1. Some people want to... but are too shy to give up their seat. (
You people won't understand the psychology of such people, the
feeling isn't good at all, you want to help, but you just can't
bring yourself to do it because of your shyness, or in Singaporean
terms "Paiseh" )
2. The person might not have noticed or realized that it was a
pregnant woman. I mean, ya, you see a pregnant woman, do you have
the mindset to immediately "Oh! I have to let her have my seat!"
No, some people don't think of that, that fast...
Besides...
Its none of my business. 
