I agree the Cadillac ELR was a poor response to the Tesla S but the Volt is an excellent car. GM didn't get it all wrong. For starters, the average person finds the Volt slightly expensive to own, nevermind the Telsa S which is even more out of range for the average Joe making it even more of a pipe dream. Another huge problem is that the supercharger network doesn't go everywhere, there's not a single supercharger to be found in NorthWestern Ontario which is fairly remote and we suffer from very extreme winters. If I owned a Telsa S here, I could never leave my city with it.
Every year I go cross country across Canada on a trip equivalent to 1,200 miles one way. I would guess that if a supercharger network existed, it would add four hours to the trip because of the need of having to stop to charge up. If you're in a rush to get through your roadtrip because I often run non-stop, then a supercharger network would definitely be slower. Cars are also suppose to be about freedom right? The fact that there are gas stations virtually everywhere means the Volt can fuel up anywhere with very few worries where I can see from your note that you need to pay special attention to where charging points are.
Tesla uses a version of Laptop Lithium batteries, the Volt uses a much safer phosphate class Lithium battery which you find in some solar lawn lights. It isn't hard to figure out the difference in the news articles. The Volt has not suffered a single battery fire in the real world except when the coolent caught on fire after it dried out. They apparently cracked open a Volt battery pack and left it in the junk yard for a week. In comparison, a Telsa S's battery pack will most certainly catch on fire if you manage to puncture it. There's no magic in Telsa's battery pack. GM decided that they would go with a safer, near impossible to catch on fire battery type but the trade-off is less capacity for weight. Telsa went the riskier way because they have little choice, there's no backup engine and running out of range isn't a solution so a rare fire from shattering the battery pack probably isn't a big deal. Except that GM knew that the public is highly sensitive to this issue.
There's also a question on Tesla's future. Believe it or not they haven't made any money as a company. Their stock sells mostly from hype. Not that GM's that different in that the Volt barely makes GM much money either but at least they are able to use that technology in their other car ventures such as in the hybrid Malibu and other upcoming cars. I don't dislike Tesla, they helped open the door to EV's but to me it seems that their future looks a bit shaky compared to some of Musk's other ventures like SpaceX.