Mainstream people snitch.
Get over it. As long as snitchin' bothers you, you will never like life in the mainstream.
Why they do it?
(1) Violence, crime and chaos are not accepted in the mainstream. They don't want them anywhere in their world, and they do whatever it takes to get rid of them.
(2) Personal responsibility is essential to order in society. Mainstream people expect themselves to be responsible, and expect everyone else in their world to be responsible also. Those who hate snitches do not want to be responsible.
(3) Empathy for the victim.
If you physically harm another person, you will get snitched on.
If you steal or damage someone's property, you will get snitched on.
Solution: Be responsible. Respect others' bodies. Respect others' property.