Poachers do their work anywhere, they don't necessarily crawl way back in the remote to do their dirty work. Some shoot from the road and some hike in to find game, it all depends on what they are after. Most like a fast getaway out of sight.
Some poach so they can brag to their friends and some poach for money. You also have the really sick ones who just like to kill animals and leave them lay.
As far as the cops or warden coming after shots being fired, that's usually not the case. I've had to call the warden and sheriffs a few times and it took hours for them to arrive usually, if at all. With the shortage in DFG wardens now all over the state you're lucky to even see a warden in the field.
There is a CALTIP hotline you can call if you do see suspicious activity.
1-888-DFG-CALTIP
(1-888-334-2258)
http://www.dfg.ca.gov/enforcement/caltip.aspx
Like any group, us hunters have unscrupulous folks who tarnish our image and give us a bad name.
As far as the Bighorn Sheep poaching, I'm not so sure it's for medicinal reasons. The horns are extremely valuable since it's really tough to draw a legal tag to shoot a bighorn ram. You can buy a limited bighorn hunt but it will cost you over 100K for those hunts, the most expensive hunts in the world. Hence the horn poaching, some just don't want to wait or have the beans to hang a big ram over their fireplace.
When you can pay an illegal 5K to go get you a bighorn ram locally it's just too tempting to some. The fines the judges levee are a joke and are no deterrent to stop the poaching. When the judges throw the poachers in jail for a couple years and fine the dog poo out of them you will see a dent in the illegal killing of game.