J. P. Gilliver (John) wrote:

(Why do [some] people insist on using that term - anal - for other
people who want to know something they don't, or similar? I find it
unpleasant. And no, I'm not one of those referred to in this case.)

It has an honourable pedigree. Freud said that children who had problems
with toilet training developed certain personality traits which stayed
with them for life: obsessiveness, over-concern for detail, etc.

It also ties in with the issue of when to start toilet training.
Possibly starting too early can cause these problems.

Bill