Don't mess around with safety.
Part of safety is giving workers meal and rest breaks. Without rest and food it is difficult to concentrate on precise tasks that involve physical exertion.
One rest break should be given before the meal break and one rest break should be given after the meal break if the shift is 7 hours or more.
Construction workers waiting for a delivery, or waiting for a concrete truck to come are not on break. That time is considered waiting at attention, and must be compensated for.
Moreover, the time spent waiting may not be long enough for an uninterrupted 30 minute meal break or rest break.