Ethics is taught. Directly or indirectly (i.e. environmental/cultural). Also for some, a loss of an employment has significantly higher consequence than others.

If you take these into consideration then it makes sense why one would make such choice. Whether they are aware of building an evil device is irrelevant at this point -- they're making best choice for themselves and their family. Employers love employees who follows orders so they'll craft environment where only those kinds of employees would survive.

IMO this isn't really the problem between employers and employees. They are doing what the system incentivizes them. It's the regulator's role to govern to protect individuals.

The irony is U.S. allows lobbying and SuperPAC which essentially makes the system in favor of those with money.