It would be unpatriotic to rescue the Indian owners of Jaguar Land Rover.
It would be protectionist and against the interests of UK car buyers to subsidise the British motor industry at the expense of cheaper cars from abroad.
It would be inefficient to keep Jaguar Land Rover alive with taxes raised on successful businesses.
It would be environmental craziness for Labour to announce extra taxes on 4x4s in the spring budget and then use those and other taxes to rescue a 4x4 manufacturer less than 1 year later.
It would be electioneering if manufacturers in marginal seats in the English Midlands get subsidy but manufacturers in the safe North East of England do not.