That's entirely true... my point is that there is no actual legislation that requires the employee to take a break... and that the employee must still be paid for all time worked unless there was an explicit agreement to the contrary in the employment contract which would have been signed by the employee when they started working for that employer. Even then, certain rights to being fully paid for time worked cannot be legally forfeited, regardless of what kinds of agreements were made.
But certainly, yes... an employer is at liberty to discipline an employee who works unauthorized hours, in whatever fashion is commensurate with that company's disciplinary policies. Even if the hours were not authorized, barring any employment contract which explicitly indicates otherwise, as I mentioned above, the employee is still legally required to be paid for the time they worked, and cannot legally deduct time for a lunch break from the employee's pay if it was not actually taken.
"Ninety percent of baseball is half mental." -- Yogi Berra