look it up yourself, it's common knowledge that migrant workers from neighbouring countries follow different rules, go to any big building project or factory even and you will find many migrant workers working legally.
Looking on your profile it appears that you are Vietnamese, many people commenting here don't realise that there are different rules for migrant workers from neighbouring countries.
I think you should direct your enquiry to your nearest Thai embassy or possibly try and find a Facebook group for Vietnamese people who are living and working in Thailand.