This is exactly how it is at my husband's high school: no penalties, no consequences, unlimited turning in of work until the end of the quarter. Didn't finish it all and ended up with a D or lower? Doesn't matter, because you can't be held back anyway.
Let's not even get into how kneecapped teachers are in classroom management. A student reported him for pointing at them and touching them when he was never fewer than 3 feet away pointing away from them. The students know they have the power now, and they're definitely not going to be told what to do.
There are other ways to introduce motivating factors that aren't tied to grade level retention. Sometimes this is done in secondary and tertiary education in the US, like preventing participation in extracurricular activities.
Let's not even get into how kneecapped teachers are in classroom management. A student reported him for pointing at them and touching them when he was never fewer than 3 feet away pointing away from them. The students know they have the power now, and they're definitely not going to be told what to do.