It's pretty subtle. Ubuntu packages, maybe not all DEBs, like to prompt for input on how to proceed with new configs.
For servers at scale with varying packages, levels, and requirements - this gets painful. Some config hackery can help, but creates a bit of a circular problem.
RPM systems (by default) will trust the administrator. They don't prompt, and provide the new config file as a reference - without messing with what's already been deployed.
Apt also likes to get hamstrung on previous transactions. If they broke for the reason I just mentioned [or any other], installing new/completely unrelated things is blocked.
I can pretty much trust my RPM systems to do what they want/have been told... but not the DEB.
Granted, my experience with DEB has mostly been limited to Ubuntu - so it could be that/Canonical.
It is not a Canonical specificity, but it is overridable behavior.
For the dpkg prompting on configuration file changes:
https://raphaelhertzog.com/2010/09/21/debian-conffile-config...
> You can also make those options permanent by creating /etc/apt/apt.conf.d/local:
> Dpkg::Options { > "--force-confdef"; > "--force-confold"; > }
Along with invoking apt with -y (assume yes) will get you close to the behavior you seek. Or as a permanent setting:
APT::Get::Assume-Yes "true";