Do the post man and post office staff open the mail?
It's completely different, you're giving people the authority to pen and scan your mail, postmen ( or women or binary nuetral humans ) do not do that.
All the things you mention are true, however Thailand is far far from being 3rd world, i take it you've never visited West Africa, now that's some poor countries.
MHS town itself is awful, nothing to do on an evening, as a province for bike trips etc, fantastic scenery.
Nan is cool but becoming too busy during 'winter' months.