At my school everyone gets a grade of at least 50%. We have two written exams that make up for 60% of your total score (30 each). Then there's 15% for listening, 15% for speaking and 10% for work effort. Smart kids who don't make the effort know they can just do well in the exams and their final score will still be good. Lazy students will always get 50% for every category. Students who are smart and work hard only score a little higher (relatively speaking) than the smart and lazy kids. Weaker kids who try very hard also only score a little higher than weaker kids who don't care.
So for example, lazy kids who do nothing will get 50%. Lazy kids who are smart often get between 70-80%. I still have to give at least 5% for work effort. Meanwhile, the students who try the hardest don't really get much of a reward. A kid can do literally sod all and still get 50%. Actually, that's a lie. If they're late paying their tuition fees, they get sod all until they've paid.