All lot more than they include. the decisions about what to include and not include

Explanation:

All maps exclude a lot more than they include. The decisions about what to include and not include introduce bias.

There is only so much that we can put on a map for it to still be readable. So the map makers need to make a decision that is based on the importance on what to keep and what to discard. Now there can be differences in maps around the world like in Russia maps have Crimea as part of Russia and in Ukraine, the maps show Crimea as part of Ukraine. But that is a difference because of political reasons.