God like profession

I've been helping my neighbour (who's a CA) and his family for months, with the usual ailments. Yesterday I asked him a question about Income Tax Return and Tax Deducted at Source and got told "kardena" (translation: you should do it), with no offer to help.

Why are doctors expected to work for free but the same people quickly send an invoice when it comes to their profession?

How do you guys deal with this