When there is an increase in the number of people who want to get around, rates go up. As a result, drivers are more inclined to meet the demand. That's how dynamic pricing works.
When more people want to get around than the number of available drivers, not everyone has access to a car. When that happens, the drivers see very clearly on their app where dynamic pricing is in effect. Since it's more financially appealing to them, they may decide to move to those areas to drive people to their destination.