You would be correct in your understanding of the word "amusement". Not many realize this when they go to a carnival midway. So the term does not apply to those working, but those in attendance. But I would like to point out the definition of which can be found in nearly any common dictionary of which this term of the word applies.
1. make somebody laugh: to make somebody smile or laugh or think that something is funny
2. keep somebody happily occupied: to keep somebody occupied or entertained by providing entertainment or an interesting task.
My area of expertise would fall in the last mentioned, interesting task.
It is unfortunate that your only recollection of a carnival is that of which you mention, "games that cheat people out of their money", as there are many great facets to this world that could be conjured up besides this. I will admit that many games of the past, and a few of present day, did and do fit this bill. However, to say that they all do would be a falsity. Much of this has stopped due to stricter regulations by both the states and federal government. Not only that, but by the many independent owners on various shows due to the fact they can lose their contract with the any said show for not enforcing this in their games.
Not to criticize, but proverbs 18:13 says,
"He who answers before listening - that is his folly and his shame."
Also, I would not be considered in the least "to be without thought", as I only attended the carnival in that capacity untill I was 13 years old. After such time I have been on the other side.