The schoolteachers of the Diocese of Worcester who teach at the Central, chancery-run schools (Holy Name H.S., St. Bernard's H.S. in Fitchburg, St. Peter's Elementary School, and St. Peter-Marian) are part of a union called the Diocesan Educators Lay Teachers Association (DELTA). Yesterday, they walked the picket lines with their pupils after authorizing a strike vote while negotiating a new contract. (Pictures of the picketing appeared in today's Local section of the Telegram & Gazette; the article states the salary ranges are from $33,990 to $61,660.)
The Diocese has responded on their website, which can be accessed here. Apparently the teachers have a generous health insurance plan (85% paid by the Diocese), free tuition for teachers' kids after one year of service, and a 401k matching retirement plan.
First of all, one of the last major decrees issued by Benedict XVI before the bogeyman forced him out was a salary cap on lay employees. Lay employees should not make more in a salary than double that of a diocesan priest's salary. (Last to my knowledge, Worcester priests made $25,000, so lay employees shouldn't make more than $50,000.) Since these schools are operated by the Diocese, the teachers are church employees.
Secondly, raises haven't been given in a while because Catholic school enrollments are down, not because only because good Catholic families can't afford it, but because they don't teach from the Baltimore Catechism. Neither the TLM has been said in 50+ years for school liturgies. With orthodoxy in question, you're going to lose customers.
Finally, church employees work for the Church. They have no business being unionized. Quadragesimo Anno only applies to private secular industry, not Church lay employees.