Of course it is a job, because someone has to do it, or has to do all the things encompassed by it. Not doing those things would be bad, would have deleterious effects on your family. They are things that have to be done.
If your family doesn't have a SAHP, all those things still have to be done, either as second jobs (or second part time jobs) by the WOHPs, or as outsourced work which other people are paid to do, or combinations thereof.