Motorcycles are prone to getting small dents and dings just like cars and trucks, there is however a fairly large exception: the metal. It's not just that most of these motorcycle tanks are far thicker than a car or truck, it's all of the components surrounding it. Also access into the recess of the tank is often limited. Having said all of that, most repairs are still possible.
When it comes to motorcycle tank repairs, it really boils down to the setup. Most dents cannot be repaired on the bike. This means that the tank will be removed from the chassis and placed on a mock chassis stand. This will allow the technician to gain the power and leverage needed to push on the thicker metal of the tank.
When pushing thicker metals, it's wise to heat the metal upon the surface. This is especially true of Harley Davidson tanks. Primarily, because of the way they tend to lay in stickers prior to applying the clear coat. Either way, its all mitigable and in most cases the dent can be repaired. However, everything in that tank must be removed. You want to remove everything because small shavings from pushing on the backside of the metal could get into the filter. Very fine shavings could make it through the filter and get into the engine. Although that possibility is highly unlikely, it's not a risk that most professionals will take.