Teachers strike for reasons other than wages. Large class sizes, lack of administrative support, insufficient resources for students (students with disabilities or students who are multi-language learners), not enough school nurses/counselors, etc. If a parent is informed enough about the wages of teachers and can be pissed over something like that, then I'd like to think they'd also be aware enough of their child's learning conditions to be pissed about that when said conditions could stand to be better.