Well, that's one way of looking at it. Traditionally, skycaps who provide curb-side check-in don't work for the airlines. In many cases, they work for contractors to the airport, so there isn't a direct cost-relationship between the providers of curbside check-in and the folks who incur the cost of checking-in inside. There's surely some power-play that goes on between the various groups involved, and it is reasonable to expect that everyone is looking out for their own best interests -- meaning how much money it costs them versus how much money they make, in light of what impact, if any, quality of service may or may not have on revenues.
It's not always a clear-cut thing. For example, adding a surcharge may increase or decrease company's revenues, depending on how likely the addition of the surcharge will affect customer purchasing decisions. Indeed, sometimes there is a counter-intuitive relationship. Some companies have experienced resurgeance in revenues after significantly raising their prices, without making any other changes, just based on how that changes customer perception of value.
I've personally observed a lot of folks stiffing skycaps over the years, so I'm not surprised that its reached the point where something has got to give.