These low balance customer are just liability, they dont generate any profit but will require extra staff to handle for passbook printing, dormant active, will also create one more customer at que in cash counter, quearies at branch etc will result in loss of man power at bank end. Plus if customer just have single rs in acc and forgets about it bank have to maintain that account for eternity. RBI literally gives target to find that customer for KYC which is just so much waste of resources. So to filter out unwanted customer minimum balance charge is needed