Facebook’s Apps Went Down. The World Saw How Much It Runs on Them.

For more than five hours on Monday, the world got a taste of life without Facebook and its apps.

In Mexico, politicians were cut off from their constituents. In Turkey and Kenya, shopkeepers couldn’t sell their wares. And in Colombia, a nonprofit organization that uses WhatsApp to connect victims of gender-based violence to lifesaving services found its work impaired.

“Because we have a field team, we were able to mitigate some of the more serious risks today’s outage presented,” said Alex Berryhill, the director of digital operations for the group, Cosas de Mujeres. “But that might not have been the case for hundreds of other hotlines around the world. Today was a big reminder: Technologies are tools, not solutions.”

The Facebook outage on Monday was a planetary-scale demonstration of how essential the company’s services have become to daily life. Facebook, Instagram, WhatsApp and Messenger have long been more than just a way to chat and share photos. They are critical platforms for doing business, arranging medical care, conducting virtual classes, carrying out political campaigns, responding to emergencies and much, much more.

In parts of the developing world, the cost of the Facebook outage was particularly acute. In India, Latin America and Africa, its services are essentially the internet for many people — almost a public utility, usually cheaper than a phone call and depended upon for much of the communication and commerce of daily life.

The unease about a single corporation mediating so much human activity motivates much of the scrutiny surrounding Facebook.

In the United States, the Federal Trade Commission has filed an antitrust lawsuit against the company, accusing it of being a monopolist that acquired Instagram and WhatsApp to secure its dominance. European Union policymakers are drafting sweeping regulations that would crimp the company’s power.

In recent weeks, Facebook has been under fire after a whistle-blower, Frances Haugen, shared internal documents indicating, among other things, that the company knew Instagram was worsening teenagers’ body-image issues even while company executives publicly tried to minimize the app’s downsides.

The revelations have spurred more criticism from regulators and the public. On Tuesday, Congress was hearing testimony from Ms. Haugen about Facebook’s impact on young users.

Much of the recent criticism of Facebook has focused on the decisions the company’s leaders make — or fail to make — about governing, running and making money from its platforms. But as Monday’s outage demonstrated, another consequence of Facebook’s size is that many more people are affected when there are technical lapses like the ones the company says were responsible for the disruption.

In Brussels, the hub of the European Union — where many government workers have turned to the rival messaging service Signal to communicate amid concerns about Facebook’s reach — the outage led to a fresh round of calls for more oversight of the biggest tech platforms.

“In the global digital space, everyone could experience a shutdown,” Thierry Breton, the European commissioner drafting new tech regulations, said on Twitter. “Europeans deserve a better digital resilience via regulation, fair competition, stronger connectivity and cybersecurity.”

In India, Brazil and other countries, WhatsApp has become so important to the functioning of society that regulators should treat it as a “utility,” said Parminder Jeet Singh, executive director at IT for Change, a technology-focused nonprofit in Bengaluru, India.

People in India and other Asian countries where Facebook’s apps are popular largely slept through the outage, which occurred overnight for them. But Mr. Singh said the disruption still showed why regulators needed to supervise the internet giants more closely.

Worldwide, 2.76 billion people on average used at least one Facebook product each day this June, according to the company’s statistics. WhatsApp is used to send more than 100 billion messages a day and has been downloaded nearly six billion times since 2014, when Facebook bought it, according to estimates from the data firm Sensor Tower.

India accounted for about a quarter of those installations, while another quarter were in Latin America, according to Sensor Tower. Just 4 percent, or 238 million downloads, were in the United States.

In Latin America, Facebook’s apps can be lifelines in rural places where cellphone service has yet to arrive but the internet is available, and in poor communities where people cannot afford mobile data but can find a free internet connection.

Cosas de Mujeres, the nonprofit in Colombia, has hundreds of interactions every month with Colombian women and Venezuelan migrant women who face domestic and emotional violence or are at risk of trafficking or sexual exploitation, said Ms. Berryhill, the organization’s director of digital operations.