Can’t speak for every place but that’s not always an option. As a teenager, I worked at Sports Direct where the management would regularly work us after our allotted hours and bar us putting the extra time onto our timesheet. If I recall correctly, the company eventually got pulled for it but the money they’d have saved over years would have outweighed the fine.
The timesheets were on paper so good luck putting your real hours on without your manager, who files it, finding out.
I’d be amazed if they ever cleaned up their act.