I sure don't look for opportunities to kill snakes but if a poisonous one and I try to occupy the same volume of space at the same time then according to my personal rules it is a dead snake. Having only killed 2 snakes in 8 years I don't think I am destroying the balance of nature.
I'm not a snake fancier and don't keep them as pets but I do grab the odd non-poisonous one for a little show and tell now and then like the one that tried to come in the house from the back porch when my SIL opened the French doors.
I probably jump as far and fast when a snake "appears" by my feet in the grass/weeds as anyone. OK not fast enough to sit on the porch and watch my image arrive.
There are lots of reasons for killing poisonous snakes in inhabited areas, where stock is kept, or where pets roam but very few legitimate reasons for killing non-poisonous ones. Mostly it is ignorance, superstition, stupidity, false sense of bravado, machismo, FEAR, or whatever...
Survival training? OK but eat it.
Pat