Because a lot of fear, outright ignorance, misconceptions, and other internalized beliefs.

In some cases people talk about “shit water running down my legs!”, so I don’t think they can visualize the water falling down into the bowl, and leaning a bit to one side to wipe dry. Or (possibly? idk) they think you stand up to use the bidet.

Another one is fear of the spray spreading bacteria around, or the like.

Then there is that the admittedly low bar for entry of installing the bidets is enough friction to not deviate from scraping-based insanity.