Just doing the coolant refill service procedure in a shop can take quite a while. It's going to take several times to build back up a vacuum after each time some coolant is pushed in. Then, running the coolant pump. I would wager it probably takes at least an hour (or more) in a shop environment.
Even a "simple" purge to get that one last air pocket out could take some time at the dealer service level.
Assembly line is kicking out a new vehicle about every 1-2 minutes.
Granted, the assembly line is set up for quick production and made to do this procedure as quick as possible.
With as complex as the Bolt is (or any EV vehicle is) the assembly line is concentrated on time & efficiency. There may be a pocket of air that might not get removed.
PDI "could" catch it but, at my dealer and most others, they did not want many miles put on new vehicles for a new customer. Can you guess how many people would complain if their new Bolt they had ordered, that just came in and is ready for the customer to take delivery, has 30 miles on it? People would be complaining more than a low coolant jug.
This might end up being a procedure that a dealer would go through with a new owner for an EV. After taking the vehicle home, for the next couple days have the customer pop the hood and check the coolant level. If it's low, call us and we will send someone out to your house to top it off. Or, give the customer a plastic container (1-2 Qt) of 50-50 Dex-cool and water to top off if needed.
I know when I take delivery of mine next week, I'm going to pop the hood every day for the next week just to check.
Besides, I have a gallon of Dex-cool for my other Chevy's that sometimes need a top-off.