I just don't think that the situation described is particularly extreme or wrong. The lady could be best described as a jerk, but i think those families who have domestic helpers eat separate from the family at home are just as bad.
As for eating with the helper watching, again this is just jerkish behaviour. We don't know if looking after this lady was within her responsibilities or not.
I would also never ask a taxi driver to wait a few minutes while I got something from a shop etc. even if I paid him. I think thats socially unacceptable too because even if the driver is willing, it wastes his time and prevents others from getting a taxi.
Not sure what you are arguing on the eating. You say the employer is a jerk, agreed.
If the helper cooks the food at home then is not allowed to eat any (which happens),I hope she spits in it (which also happens).