i don't dispute the dates of introduction of 802.11n and/or 802.11ac, but the gist of
@AmpedRealtor's comment is that what's there is "good enough". I happen to agree. Improving the 802.11 capabilities of the car probably isn't a high priority for Tesla, nor IMHO should it be. Especially not for purely philosophical reasons...it costs money to rev the hardware and I'm not sure it would result in a significant amount of new sales.
802.11g "works" for the purposes of what the vehicle does, although my position was never that 802.11g somehow "doesn't work" (careful of the Straw Man there). I would also contend the price point of Tesla vehicles is not aimed at a demographic that thinks of vehicle features in the "good enough" category.
The questions that struck me when I realized that my 2017 Model S came with an 802.11g adapter were, "Why did Tesla initially decide to use outdated technology for 802.11 connectivity? Why is Tesla still outfitting vehicles
today with such outdated technology?"
The price difference of 802.11n hardware versus 802.11g hardware is negligible, as the price of both is negligible. Effort to update the OS for the different hardware is negligible. I'll agree that there's not much motive to target this change in and of itself, as it's not a selling point and isn't pervasive like the 3G->LTE advancement. It seems like the kind of thing that could have easily been incorporated in the facelift revision though.
But, again, purporting to be a company about driving technology (double meaning intended) makes me wonder how this decision was made and perpetuated. If the Model 3 comes out and still has an 802.11g adapter, I'd consider that ignorance of technology.