Yes, travel agencies.

It depends on what you need, and what is necessary. If you want to do an ice climbing on Villarrica in Pucón, Chile, transportation might not be enough.

If you want to visit the national park on Rapa Nui Island, you need a guide for many attractions. Similar on Galapagos Island.

Sometimes only a transportation is more economical. Sometimes renting a car. Sometimes a guided tour.

Also they depend on how many you are? 1 person, 2 people, more?