Because they didn't follow the law ?
they didn't commit any crime. overstaying a visa is a civil violation. removal is not automatic. discretion is allowed especially if they have American citizen dependents, have been here 10 years +, are working, committed no crimes ...
along the lines of a parking meter violation; which on the face appeared too be corrected. most people would think receiving a federal work permit, a state issued Real ID, and a sponsored application for a green card means they are legally present. there was no intent be here illegally.