it seems that Ubuntu must have automatically made my user member within the correct groups, and also gave me the correct permissions to easily to do other tasks such as easily mount removable media.
Ubuntu is a single-user desktop as easy to use as possible for everybody turn-key OS based on Linux. Of course it's trying to prevent its users from the need to do things by themselves, which means learning, and autoinstalling and autoconfiguring as much of the most popular stuff as possible, which on a unix[like] system includes permissions.
Anyway, FreeBSD on the other hand is a multi-purpose OS, trying to be as close to original BSD ("west coast Unix"), and to support as many job purposes from firewall, router, embedded system, NAS, server, single- to multi-user desktop, and what else could be done, on a reasonable selection of supported hardware as what with the given resources of man power and money is possible.
And it tries to be - also as some kind of a reasonable compromise - as secure as possible.
This brings to consequences:
1. What you get in the first place is a fully complete, solid and already pretty powerful, but compared to many usages pretty basic OS. The idea is, all you need additionally you add yourself - tailor your own suit to fit exactly the individual needs.
What is the use of having a GUI plus LibreOffice installed by default, when you set up a headless NAS?
Instead of getting a heap of preinstalled junk - prechosen, preconfigured, prethought by others, an one-size-fits-all boilersuit - you neither need, nor want, which you have to deinstall after installation again, and then install all you need/want anyway. Just for having the comfort to prevent learning: what there is, what you need, how to install and configure it. Most are comfy with that. OK. But you cannot get an individual tailored solution by picking a pre-made one. Not everybody is grasping that. What you always can see when every now and then again in the forums the question comes up, if it wasn't a neat idea when FreeBSD comes with autoinstalling a GUI by default. *sigh*
Imagine FreeBSD as some kind of a chassis: It's pretty basic, but already useful. And for some purposes already fully sufficient. If you need something more, you build it upon it as your own: car, coach, truck, fire engine, excavator, crane... - it's up to you. Instead of getting a mobile home in the first place, strip it completely down first to get just a chassis, and then to build a bin lorry from it. Or start very basic by first building a frame, attach wheels, add a motor...
2. Security. If everything is already permitted to everybody by default, that's very comfy of course. You don't need to care about anything. Just plug in your USB flash drive and voilá, it's mounted. But if you build a server, physically accessible to other people, it may be better if not everybody can just simply stick his thing into it and gets automatic access to it. Again it's the question of having it all given by default or only what you explicitly ask for.
It's a question of the attack surface. By principle the more is installed, the larger is the chance of security holes. If lots of stuff is installed and given permissions by default, it's comfy, because all works automagically by default without any effort by yourself.
But if you only install and configure what you need, you also know what you have installed, know what permissions you gave only to what and for what you need, and you keep track of that, that by principle is safer than instead having no clue what's all installed, what permissions are given for what. Particulary not when by default the doors kept open for every possibility any user may bring. And especially not, if it's unknown there is such a thing as permissions at all. Which is another thing a turn-key OS prevents users from learning to keep things easy for them.
