Other countries can build entire rail lines entirely on viaducts for the same cost as it takes to grade separate a single Caltrain station. For example it was recently estimated that grade separating Broadway Station with a center platform would take $889 million and 5-5.5 years [1]. This is mind boggling.
Japan, sure. But Japan deals with it by going in the opposite direction: most new structures are intended to be temporary, replaced with a few decades.
Most of Europe? No, just the southern part near the tectonic plate boundaries. Which also just happen to be the most expensive parts to build in Europe...so thanks for helping to prove my point.
[1] https://burlingameca.granicus.com/DocumentViewer.php?file=bu...