Udemy course ratings have always felt absurd to me.

The few times I spent a few bucks, out of curiosity, on some technical courses with near perfect scores, was horrified to find the instructor could barely speak English, audio seemed to have been recorded out an internet cafe in some 3rd world country, and explanations were shallow or confusing.

The surprise was not that a $5 to $25 course was bad. The surprise was the mismatch with the numeric rating, reviews and student testimonies, compared to actual course content. I can only imagine, most reviews are fake and the rating system has issues.