Cargo weight vs payment

[SM8194]

Hey everyone, it's just me or jobs payments do not increase proportionally to the cargo weight? It is like distance is what only matter.
Not sure how this is calculated IRL but I guess it should count a lot, as you need more time, fuel and a bigger truck for heavier cargo.

[airbus_sai]

Different cargo types are paid differently, both in game and in real life. Look at any freight exchange platform, this for example: Direct Freight, from California, sorted by payment rate. Compare loads of similar size (53 feet, full TL) and similar trip distance, but with different weight and/or payment rate.
And here's an Eastern European cargo broker, AutoTransInfo. Same situation, cargo payment does not strictly depend on cargo weight and trip distance, but rather on nature of cargo.
I couldn't find a good open European broker to illustrate this, feel free to google yourself and play around with filters.