@Alessandro ********
I think they want to ensure people have enough income from outside Thailand to live in Thailand, so asking for payslips is quite normal.
Allthough it is not a requirement, it was already meant at the first leaflet about DTV as something that could be asked for.
Especially for soft-power I think it would be logical to ask for payslips, soft power options only cost money and 500K is not a lot when you have no income.