they send important (financial?) documents over email???? who tf does that what vendor is this

All of them.

My personal tax agent only accepts forms and sends them back via email. I had a conversation with him about using password protected zips and he just told me he won't accept them.

My hospital sent me a PDF that I was to fill in and email back with cleartext credit card information filled in to pay bills. Screenshot:

https://infosec.exchange/@jsmall/116745959468132388

I recently deal with an inheritance and the Super Fund would only accept legal documents by email. I could go on, this is normal.