Tangent: having huge price differences on "similar" routings is not sustainable, regardless of rules. There are limits to O&D price discrimination (in the economics sense)....

At some point people will make the economic decision to "game" the system (legitimately or illegitimately) or a competitor takes the business or someone reinvents the business model to give consumers what they want. In the long term, you can't "protect" that revenue against market forces (just ask the CD industry, the taxi industry, two name a couple).

Prices need to converge to a reasonable point where that extra stop is not "worth it".