You don't seem to understand fleet management at all.
Example - Appliance A is from a brigade that is busy, does a lot of strike teams, etc racks up several thousand kms a year not to mention operating hours.
Appliance B does maybe 10 calls a year, all local area and in 20 years has racked up 5000 kms, doesn't go on strike teams.
As a fleet manager why would you leave Truck A in the same brigade for 20 years and find its stuffed after 10 and needs lots of money spent when you can leave it Appliance A at the first station for 5 years, get some kms up, get some bugs ironed out and get some high usage out of it, then pass it onto the second brigade that does the 10 calls all in the local area, its still modern, nothing wrong with it, and can live quitely doing a few runs a year.
Perhaps better still have 3 levels, Busy, middle range and very quite, get maximum value, rather than spending $300,000 for a truck that will be lucky to leave the station 100 times in its life time.
Now I wait for the rants "the deserve the morale boost" "they see more fire than region 1" blah blah blah.
Its not longer the days of when the local council paid for it, so they should adopt a more stringent plan.
But of course no one wants to think of the big picture.