The ones who do are scumbags. They are simply trying to squeeze a few extra bucks out of you, and if you get caught or hurt, they’ll just replace you with someone else to put at risk. They don’t want you to cut corners to save time because they like you and want you to be successful. It’s because they’re too cheap to hire the correct number of workers for the amount of work they have to do each day.
Obviously, this doesn’t mean much for this particular job, but keep it in mind for future.