Science teachers in regular public schools are usually instructing 20 or more different kids at least five times a day. The students all have varying academic abilities and know more or less about material or skills in previous science units. Teachers need to use direct instruction most of the time as a matter of scale, and because it's actually more important for the average students to use their reading and writing skills than to learn science, since most of them won't be scientists but they will have to read and write. The "perfunctory lab" is pretty much where they are going to get everything you are talking about here.

The best source of young scientists are magnet schools that specialize in STEM, and they usually get the best teachers too. Rest assured that they are already doing a lot of what you are talking about, but it's only for the kids who are actually capable of it.