Very few people even bother to track calories. Some people do have trouble sticking with it, but for most, the eureka moment happens sometime in the first week when they realize that they are consuming far more calories than they had believed. It's not a problem of perseverance when most people aren't even bothering to get started.
If you eat fewer calories than you burn will you loss weight? Yes, of course.
Do people have trouble sticking to calorie deficient diets? Yes, that's why so many people are fat.