There are checkpoints in civil engineering projects that can't be passed without a professional engineer affixing their official seal to a document. If you are a professional engineer and you are found to have done this improperly you will lose your license, which is way worse than being fired because you won't be able to get a job anywhere else either. And civil engineers are indoctrinated into their field's ethics culture with lots of reminders of how many people died when current practices were not followed.

If a firm is found to have inappropriately (for example, pressuring a professional engineer to affix their seal inappropriately) they will lose their certificate of authorization and then not be able to do any engineering work.