Pretending that there is such a thing as equal work is a throwback to a time when many people had very similar factory jobs and, it was thought, they all did the job equally. That latter has never been the case. People have always done a job differently and it is ridiculous that people have a right to the same pay just because they do a job with the same title let alone when people do quite different jobs.
Does a dinner lady do an equal job to a dustman? Completely subjective as to whether what they should do is equal let alone the fact that they will always do their job with different attitude/effectiveness etc.