I'm beginning to think the problem with today's younger generations is they aren't learning the basics and the teachers aren't bothering to teach them. This makes it so much easier to mislead them. They begin to believe everything their profs tell them at school and we're seeing the effects of that every day.
Teachers are human, so occasionally they do make mistakes. However, it's a mistake to look at problems in the educational system and think that they are invariably caused by teachers.
Speaking from the experience of thirty-six years in the classroom, there are a lot of obstacles to instructional improvement. Teachers not bothering to do their jobs happens, but very seldom, and the effect is far less than that of other problems.
One of the biggest problems is that education has become a political football. Have you ever noticed how incumbents praise education or at least say it's improving, while challengers tend to attack it. Many of the quality assessments are politically, not educationally, motivated. And a lot of the data that's interpreted and misinterpreted isn't good data in the first place. Though some standardized tests in recent years have been somewhat better, the tendency in testing has been to assume that one can tell everything from objective test questions. That's a good mechanism for measuring factual knowledge but not a good one for measuring skills like analytical writing. The result is only a partial picture at best.
However, that isn't even the worst problem with assessment. Typically all these tests that are high stakes for the school are zero stakes for the student, at least in a lot of places (like California). In other words, students have absolutely no incentive to perform their best. State testing results for individual students don't get reported to colleges (California forbids posting them on transcripts), aren't part of the grade in any class, and just generally don't provide any tangible reward for students. Sure, there are some students will still do their best because that's the way they're wired. Struggling students will tend to score lower. Those two groups are scoring more or less accurately, at least for the elements the test can accurately measure. However, together they are a minority of students. The rest rocket through the test as fast as they can and let the chips fall where they may. For instance, I've seen students in Advanced Placement classes get a good grade in the class, score high on the AP exam (which theoretically measures readiness for college-level work), score well on the SAT, and bomb on state testing. What made the difference? Motivation. The students cared about the grades, the AP scores, the SAT scores, but not the state test scores. It it's those state test scores that are sometimes the only measure of school success. When schools have experimented with incentives, they've found that test scores rose substantially. Unfortunately, the system doesn't make it easy to incentivize test results.
Data-driven decision-making is a good idea--except when the most readily available data is garbage, and that's shamelessly manipulated for political purposes.
Aside from measuring student progress poorly, schools suffer from lack of funding (or at least inconsistent funding), systematic exclusion of teachers from decision-making in many places, and rapid administrative rotation (so the administrators often don't have much of a clue about local conditions and tend to make policy based on generic formulas rather than knowledge of the specifics). Do teachers have control over any of these things? No.
Teachers do have control over whether they stay in the profession, and one of our problems now is an enormous teacher shortage. In California, one large district started the school year with substitutes (many with emergency credentials) in 40% of its classrooms. A somewhat smaller and more affluent district started with 25%. Nor is the problem confined to California. So yes, you might now find an increasing number of teachers who are inexperienced and will probably be out of teaching before they get experience. You may also find more burned-out teachers, but that's a consequence of systemic problems, not something inherent to the teaching profession.