In my experience (as a student), what actually ends up happening is that students don't do the lectures, which leads to low engagement with the classwork. This also tends to punish people who fall behind, since class time is useless without doing the prerequisite material.
On the flip side, your ability to do homework with the teacher is limited by class size, which have to be large unless you can find a large supply of teachers and buildings to put them in. So what ends up happening is that you teach yourself, which is great if you're smart or talented enough to do that. But if you're not, it's very easy to fall behind and stay behind with this model.
Lots of students simply aren't mature enough or lack the disciple/interest to do a flipped classroom - and this will apply to any online education as well. Tech isn't going to magically change education, sadly, at least not the way we conceive of it now.
There are traditional ways of motivating student, a combination of carrot and stick.
But yeah its not been solved yet.
Mom did not mince words about which one she thought was far better for the students - in spite of having a vastly lower per-student budget.