An exemption when everyone else is taxed on the same commodity is a subsidy - the untaxed people/companies are free-riding on the rest of the infrastructure/ser

An exemption when everyone else is taxed on the same commodity is a subsidy - the untaxed people/companies are free-riding on the rest of the infrastructure/services/etc. for which the other taxpayers are paying. The result of giving a $100 tax exemption/credit is literally the same as no tax exemption/credit and sending a $100 check to the subsidized entity (except for the reduced overhead & bookkeeping on both ends).