Like there are biomedical engineer, a hardware engineer, a petroleum engineer, the agricultural engineer, etc. These people don't obviously have a united ethic of placing public benefit first. The petroleum engineer is under no obligation to think of the public good. If anything, they are obligated to think of the employer's good.
To me, an engineer is a classification that separates you from a scientist. An engineer is mostly interested in applying knowledge, whereas a scientist is principally interested in producing new knowledge. The line is blurred when scientists are interested in applications, and engineers produce new ideas during practical circumstances.
In that way, a doctor is an engineer, but I'm not going to insist that doctors professionally rebrand themselves to fit my pet perspective.