We just transitioned from Gmail/Google to Microsoft and I swear it is littered with spam and scam stuff to the absolute gills.

We have barracuda networks protection that has hundreds of emails a week quarantined and there is no shortage of spam. I get legit looking secure file requests from both our corporate side AND spam and they look identical.

It's at a point where I am not sure if any email at all is or is not legit. It's really bad. Why is this? How can MS be so poor at security and why does it feel like it's so terrible?

Check Point Harmony Email & Collaboration

You can set up auto rejection for example for anything coming from outside your company domain or a particular vendors domain if you deal with those for business. MS default server side filtering is absolute ass.