You can adjust them independently because your monitor’s width and height are different. Someone may want to be able to flick their mouse to the left and right edges of the monitor in the same time frame they can flick it to the top and bottom, or vice verse if the monitor is rotated. It’s probably useful in fps or with ultrawide/span monitor setups.

Autocorrect or comment on society?

You should not be tipping your landlord.

If they are personaly providing any other services to you, such as maintenance, you need to get those clearly itemized and paid separately from rent.