I suspect "tiny battery+generator" EVs aren't a thing in the US because:

• It doesn't sound or drive like an ICE car. It still has a battery, so gets all that range/durability "anxiety" associated with being an EV.

• It's associated with all the issues of ICE-based hybrids.

• It's not "all-electric," not quiet, so it's not percieved as a luxury car like pure EVs generally are.

• The cars that do implement this tend to be smaller, so not marketable here in the US, apparently.

• Factories are still tooled to make ICE cars en masse, not EV drivetrains.

In other words, it's all perception and marketing. And I think, sadly, it's true: people wouldn't buy them here in the US.

You do see them outside the US though.