This is the fallacy of the slippery slope. The regulation is not necessarily a first step. It can and might very well stop at the driver alert stage. To become an automatic speed limiter would be a new set of regulations, with a new debate and regulatory process behind it.
At some point along the way any use of a slippery slope became a fallacy on HN, and I'm at a loss to explain how.
Would it be more helpful to talk about it in terms of set points? You can change things a very small amount from the status quo without making people upset. Accepting a change in one direction makes it easier for them to later swallow what would have been more drastic changes in that direction.
Obviously this is a fallacy if change A isn't actually a step towards change B, but surely you can see that having accepted already installed speed limiters in all cars makes it dramatically more likely that they'll later be required to actually limit the speed of the car?
