Because they do not see themselves as one body, as brothers and sisters in Christ. Or they are too busy watching others and not the Lord.
However, if a church has enough funds what is wrong with paying for some things to be done? Maybe it would be a blessing to a willing individual who needs extra money for bills and groceries. Times are hard for many, including those who are serving the Lord. Sometimes churches hold onto funds when it could be cast upon the water Ecc. 11:1. Like a circle of blessing that would return to the church as well.