Part of the reason airlines operate uniformly is because government regulations dictate they operate in a uniform manner (today, mostly for security reasons). Still, there are smaller airports and some terminals at larger airports in which the boarding procedure is not unlike Amtrak. Could Amtrak do a better job in the passenger wayfinding area and customer service department? Absolutely. But many of the issues arise from passengers expecting to be herded like cattle (like on the airlines) and not being proactive about ensuring they are where they need to be in order to board.