It's definitely empirically true. I've watched it happen for decades. There are certainly new cars on the road, but they would have been there anyway, for the most part. If you have a growing economy people immigrate in search of jobs whether the infrastructure is ready or not.
Now, I'd rather we had enough rail to handle all those people and more, but the problem with rail is before your network is built out completely it's not very useful.
>But, the HSR project is spending money on regional light rail and conventional rail between metro areas.
Great. Then all we need to cancel is the HSR itself.
Your unsupported speculation of what you expect would have been true in a counterfactual situation is not support for a claim of empirical truth.
> If you have a growing economy people immigrate in search of jobs whether the infrastructure is ready or not.
People are not the same thing as the car trips; whether the same number of people would have been present with less road capacity is a different question than whether the number of car trips would have been.
That's empirically not as true as it intuitively seems; induced traffic is a thing.
> Personally, I think California's HSR project is stupid and the money could be better spent on regional light rail plus conventional rail between metro areas.
But, the HSR project is spending money on regional light rail and conventional rail between metro areas.