Death from a poisoned dart would be problematic, slow and painful.
A hound kills a fox instantly with its first bite. Really, yes it does. The pack then rip the carcase to bits, which is distressing to onlookers.
I have never hunted, but lived in the country and was exposed to such things when I was young. We considered it normal country pest control.
But those who breed foxes so that they can later kill them deserve nothing but contempt.
The pro-hunting lobby don't really put up very convincing arguments, though and are their own worst enemy. Also, it is the 'ritual' aspect of it all which probably enrages the 'antis' more than anything; 'blooding' youngsters at their first kill is hardly a 21st century contribution to rural pest control, for example.