Why do motorbikes pay significantly lower fees on toll roads in Melbourne?

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[...] While motorcyclists will essentially be getting cheap use on toll roads, there is no any negative effects that are significant. As such, there is no arising of an overuse of the good in this case, and there is no prove of any lead up to underproduction from funding gaps because capital has already been employed and used up. The elimination of such a free rider situation will actually lead to the sufferance of the whole system, essentially meaning the free rider scenario in this case is good. [...]

[...] M. (2013). Environmental economics and management: Theory, policy, and applications. Cengage Learning. Dwivedi, D. N. (2016). Microeconomics: Theory and Applications. Vikas Publishing House. [...]

[...] Why do motorbikes pay significantly lower fees on toll roads in Melbourne? From basic economic perspective, this may appear like a needless revenue loss for CityLink charging biker's less than half price for using the toll roads. However, charging them as such makes economic sense, which raises approximately $15.80 and $21.40 for car and heavy commercial vehicles respectively for a 24-hour duration pass. First, what makes cars to be charged accordingly are the e-tags found inside their engines, which are not found in the motorbikes, considering they need to be weatherproof and highly secured. [...]

[...] The engines found in motorcycles are much smaller compared to even the smallest cars around, thus emitting significantly less pollution than average vehicles. It's thus a strong incentive for commuters to opt for free movement through toll roads on motorbikes, as a way to reduce the amount of pollution. The aspect of excellent air quality is of paramount importance to CityLink, especially at a time when the air quality in its tunes began to deteriorate. It became one obvious strategy therefore that the incentive to use more of motorcycles on the toll roads would benefit the cause to improved air quality (Low & Odgers, 2012). [...]

[...] In essence, a public good is one which is does not exclude and has no rivalry, such that all members of the public can access it at will without depletion (Dwivedi, 2016). The toll road in our scenario is considered to be a private good, which is both excludable and rival in consumption. References Low, N., & Odgers, J. (2012). Rethinking the cost of traffic congestion, lessons from Melbourne's city link toll roads. Urban policy and research, 189-205. Callan, S. J., & Thomas, J. [...]