AIBU to be surprised to read on another thread about a washing-machine being used when no-one was home, and so many replies were that you should not leave it on!
We work full-time, if it wasn't switched on until I got home, then I would be hanging up wet washing really late at night. 
Is it so different to other electrical items left on? The slow-cooker? The boiler might switch on in the winter, that's electricity and water combined. I think