I think it's pretty cool that you're willing to help people out. I don't stop when I'm by myself, but I like for my husband to when we're together. I'll sometimes stop for a young lady when she's alone, because I know how frightening that can be. Most people have cell phones now, and can call for assistance. As for stopping at night, I wouldn't simply because I'd be afraid to get hit by a passing car.
I don't see too many people being this nice. I would just be extra careful about who you approach and how. Calling highway patrol may be best in some situations, but if they just need a tire changed or a little gas, no need to get the police except to maybe make them aware that a vehicle is stopped on the shoulder.
As for the ones that get mad, don't get upset about it. I know it's a pain that you're trying to be nice and they get nasty. You have better character than they do. If it makes you feel good to stop and help, go for it. I could only HOPE to have someone like you come along if my vehicle broke down. You're a good person, don't let the crabby ones take away from that.
