Yeah, I agree that it's technically not difficult. The trouble in the US is that every state and region in the US has different laws, rules, etc. about generation, transmission, etc. You go from Texas which is lightly regulated, not interconnected, and has 'free trade' (hello nasty freeze last winter), to states like California that are quite the opposite.
The actual supply to your home in the US is highly regulated at the state level and almost always, as far as my experience, is a monopoly in any given market. Commerical buyers in certain areas MAY be able to choose a different company based on locations adjacent, but I'm going to guess those are the rarity from my experience. But I've never been in a residential situation where I had a choice (I've lived in MO, IA, MD, SC, and FL, though over time those older states may have changed since I lived there). These suppliers might be a commercial company like Duke, a city or municipalities power & light company, or a rural electric COOP just as some examples. And the prices they set for this part of the service is usually 'fixed' by the state Public Service Commission or some entity similar.
Power generation, by contrast, is more competitive, but in only a few places (like Texas) can you actually choose your generator independent of your supplier. Most of the time, at least the supplier enters contracts with the generators (or owns the generation facilities outright) for contracted pricing that is then passed on to us as the user. Generators can range from nuclear power plants (many of which are independent), utility-owned systems, or large public works projects like Hoover Damn, the Tennessee Valley Authority, etc.
That's a simplification for sure, as there are grid and interconnect operators in the middle, etc. but you get the main idea.
Most electric bills now are broken out between the service side and generation side to show the costs for each, and the service side is usually 'fixed' and the generation side is usually scaled somehow. In my part of Flordia anyhow, we have Duke Energy. They have a 2 tier price structure for generation cost: everything below a set consumption level is priced at a lower rate and everything above that consumption price is priced at a higher rate. But again, I don't have a choice of how my electricity is generated, the mix, etc. The power company sets all that for me in agreement with the Florida Public Utility Commission (again regulated pricing).
In none of those states that I've lived in are there concepts of peak and non-peak costs, etc. That does exisit in other places in the US, so someone familiar with that should comment how it works and not me.
I can in most get a small discount for allowing the electric company to install a demand manager at your home that can rapidly cycle on and off things like the water heater, etc. to conserve power in peak demand times. But in most that was optional. Only MD I seem to recall had it as a mandatory feature.
So in almost all the places I've lived the issue of interconnecting and pushing electricity to the grid is with the 'supplier' side of the equation (regardless really of the generation side). At the point of generating whether it be a car or a solar system or whatever, you are becoming a supplier under a contractual agreement with the supplier and you have to meet certain system requirements to do so. A lot of people it seems in Florida don't install things like Powerwalls, etc. and so their power companies just kick them off the grid in the event of widescale power issues so they are not unsafely pushing electricity into a system that should be 'offline' for repair.
That's where an EV COULD come into play, but again, a homeowner is at least going to have to work with a qualified electrician and possibly their electric company to make sure they've installed the correct equipment to disconnect from the grid during an outage for safety reasons and install a net meter and enter into a net metering agreement for providing power during normal operations. Some other folks that have maybe done it can expand on that if there other requirements I haven't mentioned.
Cars, to me, are NOT net generators like solar systems. In reality, they are just energy storage when not used, all you'd really be providing is a transfer of already consumed energy back to the grid in the event of a net demand to meet peak demand. And then you'd presumably be consuming it again later to recharge your car.
And all of that is why I'm skeptical, at least in the US, that V2G is a big deal to VW. Even V2H seems a stretch with all the extra equipment required, though they could presumably provide a service that would do all that at a turnkey price for you. But it just seems like a lot to manage and it's why companies like SolarCity, etc. I think struggle to be profitable. There is just no one size fits all for the entire US.