There can be more schooling and training in engineering.

After undergrad, master’s, PhD, a postdoc or two, one would still make low income. After that, there is a never ending path where one has to constantly chase ever changing technologies. The older you get, the harder it will be to keep up and remain employed.

In medical science, you finish the residency (roughly equivalent to 1-2 postdoc in engineering), and you start to practice. Already, income is OK in residency. The older you get, the better!