It's entirely legimate to install the upstart init daemon and then construct your own events in /etc/event.d without taking those provided by the distribution.
That's why the dependency is a "Recommends", it would be unusual for them not to be installed, but it is permitted in a strict packaging sense.
Of course, you don't have a supported Ubuntu machine, but then you don't anyway because you've clearly removed the "ubuntu-minimal" package which absolutely _depends_ on them as you suggest
Not true,
It's entirely legimate to install the upstart init daemon and then construct your own events in /etc/event.d without taking those provided by the distribution.
That's why the dependency is a "Recommends", it would be unusual for them not to be installed, but it is permitted in a strict packaging sense.
Of course, you don't have a supported Ubuntu machine, but then you don't anyway because you've clearly removed the "ubuntu-minimal" package which absolutely _depends_ on them as you suggest