> which is what everyone uses nowadays anyway rather than MySQL
Um. No.
Unless they're doing something quite eccentric with it, developers will target the standard MySQL api, and the application will then work with any of the MySQL/compatible database servers:
I tend to use/recommend Percona Server/Cluster (for dev/prod respectively) but as long as the MySQL-version is compatible (i.e. the fork has the SQL/engine features your application needs) it's likely that other factors (e.g. PXC has Galera replication built in, is completely open source, and has commercial support available if you want it) will be more of an influence to the decision on which to use.
Patently false. I barely hear any talk about MariaDB whereas I still consistently hear about MySQL. Please define "Everybody" in this context, because it sounds like you've conflated it with "I".
What do you mean by "ask for a MySQL database"? If I were a client, I'd be rightfully pissed off if the developer I contracted gave me a completely different database than I requested in my stack. That's a complete breach of contract, if there was indeed MySQL on the spec sheet.
Who are you working with that would flagrantly ignore the obvious differences between SQL and MariaDB?
Personally, I've never seen MariaDB used in an instance where a simple MySQL db sufficed.
Among the many open source PHP installs for things like Wordpress, I don't know that I've seen a single install of MySQL. WPEngine, for instance, only offer MySQL.
The 10M+ pulls (and 3.8k stars) on Docker Hub suggests that MySQL is still getting a ton of use.
Facebook, YouTube and Google are still massive users of MySQL. And MySQL development is moving along (admittedly after not much for a few years). I doubt MariaDB really figures compared to MySQL in industry use, or new installs.
Worth noting they own MySQL (via Sun acquisition)