Shops love selling them since the margins are great, the local government loves them since it brings in additional tax revenue, and the tourists love them since they don’t want local bacteria to interfere with their enjoyment of authentic experiences. Mother nature pays the price. It’s a classic example of negative externality where the local businesses, the local government, and the tourists get the [perceived] benefits at the expense of the environment.
About 50 Billion water bottles are consumed every year. 80% end up in the form of landfills. 67 million barrels of oil is used every year to produce and transport them enough to fuel four million cars for the whole year. Next time you are planning to buy one, it might be worth considering alternatives. Hydration packs or collapsible bottles are an investment worth making upfront. While traveling, I usually fill them before leaving a safe place, for example, a hotel, hostel, or a restaurant, so that, I am not taking the risk of consuming unfiltered water or ending up on a remote island where there is no water fountain.