What is the "major bottleneck" for "self driving cars"? "[D]"

I was wondering if anyone here can ELI5 (or even idiot-er) could explain something about "the major bottleneck" that I keep reading about with "error processing" or whatever is "the major issue" with Tesla.

For the record, this is not laziness but practicality. There is simply too much to keep up with and I am too busy tryin' to survive.

If anyone is willing to help me, I thank you in advance.

(I just wanna keep up, but I can't …

cars driving machinelearning major self driving cars