Actually the Class I freights have their clout for the same reason that the highway lobby has its clout. More people depend on them than depend on Amtrak, and hence they have a larger set of stakeholders. There is just no getting past that reality, except in our fantasies and delusions.
Very few people depend on them, that's the thing. They overestimate their clout badly. "Switching to the highways" is a thing, and it happens every time they act like idiots.
They have a TINY set of stakeholders. Mining (including coal, which is dying), bulk agriculture, chemicals, and a few large trucking companies. Many of those stakeholders (particularly the ag and chemical groups) actively hate them and are campaigning for rate regulation. There are also small shippers, but they *really* detest the way the Class Is act. The trucking companies will use the Class Is if it's convenient but obviously have no loyalty at all.
I follow the industry, you know.
I guess based on what I know of the history that they've been overestimating their clout since the 1950s, so it's a business culture thing. The younger leaders seem to understand the situation better than old fossils like Hunter Harrison; I haven't seen BNSF or (post-Harrison) CP trying to throw its weight around in the sort of stupid way that CSX has been doing. Nor has UP since the Sunset Limited hissy fit, which never made it to the attention of legislators or the general public anyway. Cooperative, cooperative, cooperative, "but we need to be compensated", is the pitch from those railroads, and it works better.
CSX, though, ye gods, attitude problems everywhere. They have much less clout than they think.