Simple answer is that while I could afford one I don't need one.
I share custody of DD with ExDH so she spends every other week at his house, so two weeks out of four there's only me at home which is a small two bed flat. Whilst it would be nice to not have to do the cleaning after a full 10hr day at work I would not be able to justify getting a cleaner to clean up after me when it takes just 20 minutes every day to keep things maintained.
Because we only live in a small flat I can focus extra time on each room once a week - my room, DDs room, bathroom, kitchen, hall, living room - and keep on top of the daily maintenance cleaning even if I only spend 20 minutes cleaning a day.
So on a "normal day" I will give the kitchen sides a wipe down as I'm cooking and do the washing up after dinner but on "kitchen day" I will spend 20-30 minutes doing that as well as wiping down all the appliances/oven/hob, mopping the floor, cleaning the sink etc; each day I make the bed and open the curtains but on "bedroom day" I change the sheets, hoover, dust, have a general tidy round etc but it rarely takes more than half an hour due to the size of the place and the fact we keep things generally tidy etc
Twice a year I book a day into my diary to do a proper deep clean - moving furniture to hoover underneath, washing windows, dusting skirting boards etc - where the flat is scrubbed and tidied in it's entirety top to bottom, but on a weekly basis there's maybe an hour's worth of cleaning to be done so it's really not worth me paying someone to do it for me when I can just take a few minutes a day to do it myself.