In the US there are speed traps in small towns already where it's known that it is a major source of government income. To be somewhat fair, people often speed through these small towns they'll never see or think about again and cause issues.
Outside the US, it's somewhat less common for units of government with the power to levy fines to be anywhere near that small. In the UK, "safety camera" income goes to national (Westminster, Scottish, NI) government, not local government. And to the general fund, not to any road- or policing-specific department.
