The principal reason for this is that lots of us here in Europe neither want, nor need them.
Mass transport in Europe is better funded and more integrated in general. It's not a second class option, especially the major cities, where often you don't need a car at all, or to be stuck in traffic in another car, whether it has a driver or not.
The geography, and especially the topology of European cites, with road networks that are significantly different to most North American and modern Chinese cities aren't amenable to autonomous cars that aren't always good at navigating those topologies. Think of how bad some of Elon's dustbins are at it.
... and finally, those of us who aren't using public transport might just sometimes want to just drive, because there are lots more enjoyable driving experiences in Europe.
There just appears to be this constant inability in the minds of corporate America that other places don't have the social conditions, seemingly lack of concern for driver or pedestrian safety, or the physical characteristics of the USA to necessitate what they are selling. These are not European defects, merely differences, and we're quite happy with them, thanks.