This very subject comes up weekly on the Volt forum with newb owners who are pissed.
It may have been covered here many times, also.....
It's a lawyer thing. I don't know if any other EV's do it this way.
The usual answer is: RTFM. But I won't say that this time.
What's sad is in the early days of the Volt they'd hand off a Volt for a multi-day review and never mention, "Oh, BTW, you got to select 12A every time
when charging with 120V. It buried in a bunch of finger taps, somewhere..." Then you'd see articles about "Volt takes forever to charge on 120V ..."
The Gen 2 Volt at least lets you select your home location for always using 12A with the GPS system knowing where you are.
If you're into EV's you have to get an L2. If you are paying to have a 240 V outlet installed, go BIG now (7.2kW) . You know this won't be your last EV!
Used '14 2LT w/ DCFC. +76 K miles.
Mostly free charging! Only one LONG visit to the shop....
GM needs Modern Troubleshooting tools for Modern EV's.
3 step Trouble Tree, 2nd guess not covered by warranty and cost $800. 3rd guess fixed the problem.