Why medically unable is fidiya the penalty for not being able to fast. doesnt match the mercy in other areas. everyone give fitrana. why would an ill person get financial penalty for being sick as per creator decree, other pillars dont penalise the 1 not able 2?
We pay because doing any kind of worship is a privilege granted to us by our Lord, ie. pay to pray. Give infinite thanks that even the sick one will be granted the blessings and rewards of that fast without actually fasting.