Compute limits what you can run realtime. Not saying self-driving cars would necessarily be here today with more compute, but comparing with language models, self-driving car computers could run only models like GPT-2. There's quite a big difference from that to ChatGPT. Is self-driving an easier problem that requires less than language models? Perhaps. language models somehow try to compress all the knowledge on the internet (not entirely successfuly yet), so maybe that somehow needs much more than self-driving, a single human can drive a car after all.