My monitor has audio out, which I plug into speakers... both have their own volume, but I'd rather use keyboard controls, but I can't, OSX disables volume control completely.
Also, you can't have a window span monitors. It only appears on the monitor that has >50%.
Links opened from non browsers open in the window physically closest to the opening app (ish). If you run chrome with multiple profiles, you can't just expect the most recently used window to open the link, you must position the window with the profile you want to use overlapping the other browser, often requiring me to drag a window fully to the other monitor (because windows can't span monitors).
OSX is the worst window manager ever created. There are states you can get into with your mouse that you can't reverse without a obscure key combo. Window snapping took how long, and it's still the worst. you can't make a window be as big as it can be without making it full screen.
It's just the worst.
I've been told I can fix all of these things... if I buy 10 different $10 apps.