Maybe it's distro specific but I'm fairly sure mysql by default installed with skip networking around 2012, and with bind-address set to localhost since then. Also the root user is only configured from local by default but I'm not sure if that was true 14 years ago.

If the defaults are more secure than your examples, it's not fair to blame the database or the defaults.

And personally I hate it when software forces security requirements on me. Maybe I don't need an admin password. It's one reason I gave up on selfhosted gitlab - there was no option to reduce password complexity for my users, and those users were only connecting from the local network. The other reason being that it spammed 100GB of logs in a month and was using 11GB of RAM before I'd even gotten around to setting up the first repo.

MySQL installed with skip-networking was very common, but as soon as you need to access it over the network (e.g. when you move from one box with MySQL and PHP to one for each) then you have to enable networking and everything falls apart.

Also, the number of times in my career that I've googled a problem and seen some forum post saying "Oh, just run chmod -R 777 /var/www/wordpress/uploads/ and it'll fix that" "Great it worked thanks!" tells me that it's the blind leading the blind out there and I'm sure there's tons of forum posts telling people how to disable authentication on their MySQL and disable iptables on their server so that their PHP app can connect to the DB without a password.

You should use a user directory (AD) and then use single sign on (SSO) or or the like. It feels kinda stupid at first, but when you have many users and many apps the AD will make life easier and with SSO users can sign in with one click of a button.

Most software matures to the point that sane defaults get set. In the early days, one could be forgiven for making MVP as the security and attack vectors were still growing. Now that attacks have matured, and new software that is released without mitigation of these mature risks is just dumb and lazy and deserve no forgiveness for being released that way.