Different Bidirectional Character Types

[Andreas Prilop]

On 1 July 2022, Asmus Freytag wrote:

>> Why do Hebrew letters and Arabic letters have different
>> bidirectional character types?
>> https://corp.unicode.org/pipermail/unicode/2022-July/010191.html
> 
> If this is not explained in the text of UAX#9 can you point out
> where there explanation would need to be improved?

I cannot find an explanation *why* Hebrew and Arabic letters
should behave differently.

Why “555-2368” after Hebrew letters
but “2368-555” after Arabic letters?

Why “31-12-1999” with Arabic-Indic digits
but “1999-12-31” with Persian letters?

Why?