What I’ve seen: most big companies have one or a few Oracle databases and hundreds or thousands of “all other DBs”, including licenses for MS SQL Server.

It's interesting that Alibaba cloud and Huawei are ahead of Snowflake

It's extremely possible to have never run into an Oracle DB in an entire career (in the depts you worked in), and moreover it's quite possible to use one database in finance and another in engineering or operations (Postgres or cloud). It merely means you haven't worked at the type and size of organization that tends to license Oracle, or more specifically only in some depts. And sometimes the org didn't voluntarily pick Oracle for technical reasons, it was mandated by the end-user, or for compliance, or application stack, or Oracle's sales team beat out technically superior/more cost-efficient competitors.

None of that is denying Oracle exists.

And that isn't even an 'issue', just an observation. I imagine this used to be similar with encountering IBM DB2 or SAP or Amdahl or melamine deskphones and partitions, but I assume you wouldn't say those are issues.

Pretty sure the most populous animal species on earth would be some type of insect, probably an ant or a locust. According to wikipedia there are estimated to be over 1.4 billion insects for each human on Earth. Rats are numerous but not nearly that numerous.