TBH this is not my experience with Gmail. Some mails randomly get classed as spam for unknow reasons while many are missclassified ("promotion" whereas it was a direct message and "primary" for a lot of stupid promotional stuff").

And legit important mails ending in spam (mostly billing) is a huge problem for many companies I know. On the other side you can spam without issue and end up in the primary box when you switch servers and providers frequently enough and target a small amount of people (under 100 000).