I used to try to have a short quiz in every lesson I delivered, typically between 10 and 14 questions. They were designed to reinforce the contents of a short presentation I would give at the start of the lesson. At the start of term I got groans when they found out they were going to have a quiz. After a few weeks there were groans and moans if I did not have a quiz.
So perhaps they regarded my Moodle quizzes as fun. Note that the quizzes were low stakes and quick. Sometimes a student would say "can I do it again to get a better mark, or is that cheating". I would say something like "you call it cheating, I'll call it learning, keep doing it till you get the best mark you can".
The most common use of the word quiz in the UK is to precede it with the word pub. Advertise a quiz and the pub attracts more custom. However if a pub advertises an exam.......
Marcus down for two seats! We are going to the game!
When you put a Quiz Score block that lists the top 10 scores of a Quiz, students love to see their names on the top of the list. It becomes a kind of Leaderboard and that encourages and motivates them to score as high as possible on the Quiz. If the Quiz allows multiple tries and is randomised (of course), then you have a very effective learning tool.
All of that is true, but...
It's perfectly possible to get groups of students who are in no way competitive. I have a couple of groups in a secondary school at the moment who simply don't care. They are all quite good - in fact some of them are very good, but they feel no need to show this. Getting an A, a B+, a D or an F results in pretty much the same reaction. I have introduced some gamification aspect (and plan to introduce more) but very few react to it.
You can be equipped with the best teaching tools in the world (and for that matter you can be the best teacher in the world) but if the learners refuse to accept the point in learning something then the effect is minimal. If the name of your school tells an employer that the kids are probably not very bright then it's no surprise that the kids become extremely resistant to motivational input.
An interesting aside. I introduced a cross-class ranking system to see who was performing best in the whole school. The teachers are extremely interested in that! It's generated quite a bit of productive discussion about why Teacher X or Teacher Y's kids are not ranked higher.
Sorry, your post was badly timed for me - yesterday was parents' evening. I'll go and let off steam in a blog post!
All the best