Because we need to add one more person to the PERS rolls...
The City of Portland Announces an OPEN Recruitment for: Auto Body Restorer
Approximate Monthly Salary Range: $3,799 at entry - $4,127 after six months
The Auto Body Restorer is responsible for restoring or modifying all types of vehicles and heavy equipment operated by the City, including performing straightening and aligning, and restorative repairs.
Many companies have a fleet of vans. Almost none of these companies have their own auto body restorers. Why not? Because it's cheaper to get an account with a local auto body shop and get a discounted rate for using them exclusively. That way, you don't add another employee to the rolls who will get benefits.
Portland has a large fleet of vehicles and the local businesses would love to have a chance to bid on a contract to be the shop to fix them. But since government doesn't have to worry about making smart decisions with money and since governments main job is to grow itself, it insists on keeping everything in-house.
Heck, why not just manufacture the automobiles yourself Portland?