Consumers were burdened with having to pay more for cars when cheaper subsitutes were available. The reduction in trade traffics in the car sector caused a significant distortion on the foreign exchange market disfavoring M'sian goods abroad. Developing a less capital intensive and more labor intensive industries, like producing car parts instead of a whole car, would have been a better approach back in the 80's. As this industry grows it can develop into a car industry. Secondly, although the infant industry argument was ligitimate enough, the implementation of it was less than agreeable.
Parents first give plenty of nurturing to a child.
As the child grows, the nurturing should be lessened, as it will encourage the child to grow and stand on her two feet. Similarly, as with almost all infant industries in the world, Proton got too spoilt and have no incentive to grow up. Over the years since Proton's inception , there have been no sign of reduction in the nurturing. As for generating revenues from tariff, this is a mistake that many developing countries made. Tariff revenue, as any economics principle text will tell you, does not outweigh the higher prices consumers pay.