We stick with the option that already comes pre-selected.
When you install a new app, you almost always accept the settings already pre-selected by the developers. Faced with a decision that's difficult or not very relevant to us, we tend to trust the option suggested by whoever designed the choice context, instead of actively changing it.
A study in the United States looked at what happened when workers were automatically enrolled in retirement savings plans. Savings rates rose at every stage (participation, contribution rates, asset allocation, and post-retirement withdrawals), even when participants were told they could opt out of the plan at any time at no cost. Amazon uses the same principle by making Amazon Prime, the plan that bundles all its services, the default option over subscribing to each service separately.
Changing a preset option takes effort, and that effort, combined with the uncertainty of whether it's even worth changing, leads most people to simply keep it.
Source: Beshears, J., Choi, J., Laibson, D. & Madrian, B. (2006). The Importance of Default Options for Retirement Savings Outcomes: Evidence from the United States. National Bureau of Economic Research, Working Paper No. 12009.
Getting the default option right in a form, a subscription, or an enrollment in a social benefit is one of the design decisions with the highest real impact and lowest implementation cost there is.
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