"OP, the martyrs are us working mums who do everything SAHMs do, AND earn our living."
"what you do, other people have to do as well ON TOP of working all day."
But LaGuardia, and josephine too, as you've posted a similar view - your statements are a contradiction in terms, isn't it? As a SAHM, I take care of my children during the day; when I was a 'working mum', I went out to work, wasn't with my children during the day and paid someone else to take care of them.
On that basis alone a working mum physically cannot do what a SAHM does in terms of actual daily childcare. Unless you work as a childminder, it is pretty much impossible to do paid employment and take care of your DC at the same time.
General domestic family tasks are another matter of course but plenty of parents who work outside the home will get a cleaner/pay someone to do the ironing and so on. Obviously many more will not be able to afford this and for those families then yes, the working parent role will be a lot more tiring and stressful.
It is simply not possible to say that working outside the home is easier or harder than being a stay-at-home parent and vice versa. It depends on the job that you do, the ages (and temperaments and needs) of your children and a load of other variables.