Not so sure about the "safer than planes" - planes are pretty safe really. Also I think the initial acceleration would be uncomfortable for passengers if they somehow retained consciousness.
Edit - the US navy rail gun apparently produces 60,000 G, humans black out around 10.
You might just about be able to do SF to San Jose with a glider and winch launch if they improved the tech 3x or so. Longer cable etc.
Time is a major component of g force tolerance. Healthily people can take 15g’s for short periods without issue, but extend that to a minute and it can prove deadly.
In ideal conditions linear acceleration to Mach 2 at 5, 10, even 20g is fine. But, if you want to go much faster the limits are reduced significantly. The Soyuz for example can hit 8.5g’s for about 60 seconds in some situations which adds up to ~Mach 14.6 and is a rather extreme situation.
Edit - the US navy rail gun apparently produces 60,000 G, humans black out around 10.
You might just about be able to do SF to San Jose with a glider and winch launch if they improved the tech 3x or so. Longer cable etc.