I won't go into details but you seem to be assuming specific, relatively unsophisticated methods. Also, not everything you mention is available or useful and it's not close to enough to for more sophisticated frauds.[1][2] Keep in mind that most ads are paid on a per-impression basis - the main reason to simulate clicks is because at some point people will notice if a specific site consumes a bunch of impressions but doesn't contribute any clicks. Ad-tech companies tend to be competent in ML since it's necessary for optimization, but fraud remains a hard problem.

[1] https://www.buzzfeednews.com/article/craigsilverman/porn-run...

[2] https://clearcode.cc/blog/rtb-online-advertising-fraud/