In the 21st century, level-platform boarding is just one of those features taken for granted in new passenger rail construction.
Except at Caltrain.
Caltrain has released plans for the “shared corridor” concept with high-speed rail. Incredibly, Caltrain is stubbornly clinging to 8″ platforms. The low platform height means anyone in a wheelchair, or with other mobility issues, will still have to suffer with wheelchair lifts or ramps.
That this is happening in the Bay Area is all the more remarkable. The Bay Area played an historic role in passing the Americans with Disabilities Act, and has an active (and litigious) disabled community.
Bob Doty, Caltrain’s High-Speed Rail Program Director, frequently refers to the $10+ billion makeover as making Caltrain just like BART. Far from being like BART, the new Caltrain is looking more and more like the old Caltrain.
8-inch Caltrain platform on the left, 2' HSR platform on the right (click to enlarge)
Systemic Failure 
Considering Amtrak’s capital corridor runs on caltrain tracks, and theyre plannong on extending to Salinas, and eventually south of that, isnt it necessary to have low platforms?
Amtrak trains do have level boarding, because they have two floors.
You can board a high train from a low platform. You cannot board a low train from a high platform.
Salinas service has been under consideration for decades. If and when HSR opens to Gilroy, CC service to Salinas will be an even lower priority.
Moreover, your idea is the worst kind of lowest-common-denominator engineering. Tens of thousands of Caltrain riders would be inconvenienced to accommodate a tiny number of Amtrak passengers. Since Santa Clara and San Jose stations have ample real estate, a much better solution is to build a special-purpose platform for the one or two Amtrak museum trains.
Hilarious title.
No, Amtrak trains do not have level boarding in the western US. In fact, there is no American or European train with a floor just 8 inches above rail level–there simply wouldn’t be room for the floor sills. Superliners and other freight-like vehicles have 18-inch floors. Bombardier bi-levels have 25-inch floors.
One theory is that Caltrain would rather do crazy San Diego style drawbridge platforms than to challenge the almighty CPUC. There’s always an expensive, inefficient, unreliable technological solution to keep small fry like Caltrain from running afoul of two big regulatory agencies with conflicting rules.
Another theory is that they still don’t know what’s good for them and that the right time to pursue a waiver of CPUC GO26-D was, um, ten years ago. Better late than never?