The trade income is actually calculated on the linear distance between the markets without taking into account the map size and the proportional amount of resources generated, thus the weight of the income and trading with players.
By scaling the trade income with the map size, the trade income won't get higher priority over gathering, which should be the primary source of resources, and will allow players to benefit from shorter trade route in smaller sized maps.
Here is a table showing the current and the proposed values took from tests made in random generated Polar Sea map and compared with and without the unlock of trade improving technologies:
| Current | No techs | Full techs | Proposed | No techs | Full techs |
| Tiny | 13 | 18 | | 26 | 35 |
| Small | 23 | 31 | | 30 | 42 |
| Medium | 54 | 72 | | 51 | 70 |
| Normal | 90 | 121 | | 70 | 95 |
| Large | 131 | 177 | | 85 | 115 |
| Very Large | 166 | 224 | | 92 | 125 |
| Giant | 232 | 316 | | 113 | 155|