That is really interesting and helpful information.
I was an early subscriber to EVGo when the monthly fee was $15 and not applicable; but offered enough savings on the per minute charge that if I only did two 30 minute charges per month, the savings exceeded $15.
With their newer plan, of course I switched to $10 per month applicable, but now I do not make as many trips to Northern California (EVGo in San Luis Obispo or Chargepoint in Paso Robles) or just "joy-rides" around Southern California to enjoy my BoltEV and explore different DCFC charging opportunities and nearby restaurants).
For example the Chevy dealer in Santa Clarita has a 24/7 DCFC available for free which I have used in the later evening hours (although Plugshare comments indicate that during business hours, Chevy EV's not purchased at that dealer have been bumped off by customers).
I also carry FOBs for Greenlight, Blink, and even Shorepower for use, when needed, at the Flying J Truck Stop in Frazer Park, at the top of the Grapevine with my AV Turbocord and adapters that I carry in the back.
I have made the roundtrip from LA to Las Vegas using EVGo in Victorville.
You keep quoting $3 per gallon for gasoline in your computations to compare electricity to gasoline. Is that really how much it costs in your area? The Flying J Truck Stop I mentioned was usually the cheapest 87 I could find (just over the Los Angeles County line in Kern County) and it is current $3.32.
Do you have any idea how much it costs you to charge at home? In my Volt days, I computed that a 40 mile day cost me $1.60 and It cost me $40 per month driving an average of 1,000 miles per month.
Good that you enjoy your SparkEV and thanks for being a pioneer!