What does ‘woe’ mean? It means ‘warning’. It’s not unlike the word we use to stop a horse – whoa! Whoa means stop. Jesus wants the neglect of the poor to stop. The poor need more than a pat on the head.
The Pharisees’ gifts were based on performing religious duty to a prescribed amount. The reason God instituted tithing in the first place was to teach the importance of caring for others. Tithing was instituted by God in Israel as a means of showing one's love for him by supporting the Levites and priests who carried out the services in the temple, as well as by having money and means available for the aliens, strangers, widows, and fatherless. (Deuteronomy 14:29.)
Here’s the fraud – they put money in the plate to see God’s work be done, but they had no personal interest in being just towards the needy. They gave out of political correctness instead of a loving heart towards God and the community.
Giving is always a two-sided coin. One side is to God, the other to bring justice (fair treatment) to people who need help.