I think domestic staff that are employed full time to serve one family can be considered servants of sorts (excluding nannies for some reason according to my friend who's head housekeeper/servant for a Duke).
Domestic staff, hired in cleaners, gardeners etc are not servants.
If you employ anyone you're employing them to serve you in some way, so if a cleaner is a servant, then so is anyone else in emplyment.
I think its not worth even getting in a tiz about.
Slavery is a whole different kettle of fish.
Being a servant isn't in any way exploitative or shameful for either the employer or employee.
As for being tax deductable/having tax breaks... I really don't see the issue. DH is self employed and there are certain things that are tax deductable as they are directly related and necessary to his work and come under expenses. My only gripe would be that a self employed person pays more base tax, and so expenses are very important to bring the tax into a more representative and fair tax bracket, PAYE have that built in don't they? I may be wrong.