Engineering horror Memes

That sign is basically legacy code in a nutshell. Some engineer 15 years ago decided to save 20 bucks by wiring the light switch to the elevator control system, and now we're all hostages to their terrible architecture decisions. This is exactly why we preach separation of concerns. Your light switch should do ONE thing. When a junior dev asks "why can't I just add this feature to the authentication service?" show them this picture and watch their soul leave their body.