Reading your post Zion, I might get the impression, that you have never had a bad thought in your life. As what you appear to be saying is that 'normal" people don't have wicked thoughts.
My view of "normal" has changed over the years. Good people can do bad things and vice versa. By the same token, good people can have wicked thoughts, maybe not as frequently as some I admit.
My conclusion is people are complex. A life of dedicated prayer might iron out those less desirable thoughts. But I would hazard a guess that Christian monks may have a worse time time than most, in dealing with wicked thoughts. Here I am referring to sexually related ones.
I mean, if a person sometimes responds angrily to a rude driver, and sometimes doesn't, what is the normal way to respond? They can't both be normal responses. One of them must be an "out-of-character" response. So I refer to children because they have been least corrupted by the world, and it gives us an idea of what is normal human behaviour.
Of course children don't drive cars, but they do have to share in other ways. One example I remember vividly, is a baby in church eating a cracker. His brother being three was drawing on the table. He saw his baby brother's cracker and wanted it. Mother took the cracker, broke it, gave half to the big brother. Baby didn't know what was happening. He saw that his cracker was half the size. Big brother pulled a face at baby brother and ate the cracker. Mother said to baby "you have to share". Baby was hurt in his heart because big brother did it to bully him. Baby didn't respond with anger so as to try and hurt big brother, but with anger saying (non-verbally) "hey! Say thank you!". It showed me a lot about how the tendency for a judge to rule does influence the likely behaviours of those subjected to the judge. In this case the mother was a wicked judge, giving her strength to bullies. The big brother didn't even need to plead his case, the mother already did the pleading by saying that he is entitled to half the cracker on request. Consequently, even though big brother did not think much of the cracker, the baby received very sore treatment that left him shaken in the spirit and although he did forget the event after a few minutes, his joy had been robbed.
From that example, I can see that if a person cuts in on the motorway, it is usually ok if they innocently need to. It usually is accompanied by gratitude. However there are lane-hoppers who care nothing about pushing others back, and it generates a spiritual climate of rudeness - the people are treated with disregard and therefore they begin to treat others as people who disregard them.
Similarly, the baby will learn to eat the cracker in seclusion or haste, to avoid the risk of covetousness - but he will forget how to love having his cracker because he is rather in fear of losing it. Thus, sin spreads to all because all do sin.
In terms of thoughts, it is the heart that gives room for thoughts. For instance, the first time a child sees sexual activity it disgusts them. Then as the world encourages them to explore it and accept it, their heart develops some sense of desire for it. Once a person has developed a sense of taste, how can they not be gratified by that taste? I don't know really why you say a monk would struggle with it more than others. In my mind I would think they probably have got rid of all sources of temptation...