No matter what kind of project is planned, equipment of some kind will be necessary to get it done. However, not every company can consider purchasing such equipment themselves, then employing a skilled operator. They may be able to lease it at an affordable cost, but there is still the question of getting an operator; one that is skilled enough to do the job in question.
The way to solve the dilemma is to hire both the equipment and its operator for the duration of the project, or for the length of time it is needed, which may not be for the whole time of the project. Equipment hire will save a great deal on the cost of purchasing a large piece of equipment that may only be in use for a day or two. It also saves the problem of where to store and how to transport it to the project site. If those costs have to be added to the cost of the project it may end up costing more than the owner is willing to pay.