You're not wrong, but the answer to "why not just do this" is because those people probably don't know about bidets, because it's not very prevalent elsewhere i

You're not wrong, but the answer to "why not just do this" is because those people probably don't know about bidets, because it's not very prevalent elsewhere in life (in the US especially). Lack of knowledge is a problem when you're poor too. If bidets were ubiquitous in the US such that just about everyone has used one, you'd not be seeing this issue.