Things like Positive Train Control (which is erratically and incompletely implemented), investing in parallel tracks to allow more interleaving of service and in more rigorous (but sensible and properly funded) safety measure are all relatively modest investments that could put a lot more cars on the rails.

> The private freight carriers are doing a fine job

Yes they are, for freight and they have zero incentive to share. If the costs for making it painless for them to share are mitigated, then everybody wins.

My original point is we're flushing money down the toilet in foreign lands and if it was redirected into an investment like this would be money better spent.

We're never going to have proper high speed rail, but at least we could have medium speed rail...

No everyone loses when you add cost because you want to add some passengers to a system that is expressly hostile towards passenger train needs. Cost add affects everyone including the poor who won’t benefit.

Do it new and stop trying to take from someone doing a damn good job.

I was arguing to make the system not need to be hostile to passenger needs by improvements of the existing infrastructure.

The other point that I failed to emphasize is that I'm working with the primary assumption that getting the necessary right of ways would prohibitively expensive and in some cases close to impossible.