Much like UPS targeting boxes, this is 100% not OK, and as a professor, if I found out my TAs were doing this, they would quickly find themselves someplace between "disciplined" and "fired".
I assume you are a responsible professor. From my experience, most professors if not every only cares about their research.
Teaching is like a job not giving them any positive feedback, so why they care?
And TA-ship is usually paid by school meaning no professor can fire TAs.
This is sadly common, but I'd like to assure you there are many of us who are interested in pedagogy, and measure our long-term success on the success and learning of our students.
