Well, they don't really. Birling is a strong traditional, conservative, British capitalist, and he has a lot in common with Margaret Thatcher, who believed there was no such thing as society. J. B. Priestley, as the play outlines, did not agree. Birling, though sticks to his view, and, though he is shaken up and frightened a little, he doesn't change his mind.
Here he is at the start of the play:
A man has to make his own way - has to look after himself - and his family, too, of course, when he has one - and so long as he does that he won't come to much harm. But the way some of these cranks talk and write now, you'd think everybody has to look after everybody else, as if we were all mixed up together like bees in a hive - community and all that nonsense. But take my word for it, you youngsters - and I've learnt in the good hard school of experience - that a man has to mind his own business and look after himself and his own...
That, I think, gives you the gist of Birling's attitudes. At the end, though Birling is pleased to have got it all over with: he even mocks the Inspector's statement that 'you all helped to kill her'. His consicence has absolutely recovered: it is as if nothing has happened.
Sheila and Eric do learn from their experience. Yet Mr and Mrs Birling both remain steadfastly rigid in their attitudes. Until, that is - that final twist!
Hope it helps!