Translators are expensive...
Translation is labor-intensive and time-consuming. To deliver high quality translation, it requires skills and expertise that only professional translators possess. Professional translators, like doctors and lawyers, need many years of learning and practice to get qualified. That's why they are expensive.

... and company expenses are high.
Translation gets even more expensive because you usually purchase translations from a translation company. The tasks like processing orders, handling files and contacting translators are time-consuming. That results in significant expenses. The companies will add a margin on top of translator fees to cover their expenses, which can be 50% or even more of what you would pay for the translation itself.