I don't like generalizations, but it is rumored that coach passengers don't tip as much as sleeping car passengers, probably based on the fact that the sleeping car pax feel,as though the meal,is free - which it isn't - but they aren't presented with a bill - while the coach passengers are! I have seen coach passengers enter the dining car, take a look at the menu and leave, based on the prices! Perhaps, as has been suggested, a coach menu with more reasonable prices would attract more coach passengers - or maybe a moderately priced special for each meal. So, again, based on generalizations, more coach passengers would not necessarily mean more tips!