There needs to be some middle ground in these discussions. Yes, it's silly to ignore realities like "how was the electricity powering this car produced?" OTOH,

There needs to be some middle ground in these discussions. Yes, it's silly to ignore realities like "how was the electricity powering this car produced?" OTOH, since we're talking about potential future solutions to a hard problem (hard relative to cars, for now)... you kind of need to dismiss current issues if they're solvable to in theory. Price of electrolysis hydrogen now, when we're not using that much of it is not necessarily indicative of potential prices at scale. To me, I think we need to focus regulation that gets high potential technologies (eg electricity production and electric transport, atm) past the point on their learning curves where ordinary price economics and/or bans on carbontech can take over. The problem with marginal mitigation like discouraging flights or large ICE engines is that gains are one-off, and not en route to bigger solutions. I agree that commercial flight is a big problem. I'm just skeptical that carbon austerity can amount to more than a rounding error in the long term.