I think the problem is encouraged because there are some teachers out there who have experienced having many adult beginners quit. Adults don’t have parents to force them, or bribe them, to go to lessons when it gets tough. They are driven to practice and continue lessons through their own motivation alone, and that is what’s so challenging about learning violin later in life. Because of this, I’ve known some teachers who don’t want to take on adult beginners since they don’t want to watch another person get easily discouraged and quit. In a way, it is a self fulfilling loop.
However, with how many adult beginners I’ve spoken to through this community, I think that way of thinking is starting to change. Instead of parents “making” you guys learn, this community is full of people who encourage each other and offer help when needed. Sometimes that’s all it takes to stay motivated and not quit, and that’s really awesome!