Welcome to America, World Cup visitors. Don't forget to tip.

Millions of World Cup visitors are experiencing American cuisine for the first time and there's one menu item that's completely foreign: tipping.

Why it matters: Many restaurants in World Cup host cities are adding 20% gratuities to customers' bills this summer to accommodate international fans who might otherwise accidentally stiff their servers.

What they're saying: Teneshia Murray Butler, owner of the Atlanta-based chain T's Brunch Bar, tells Axios she raised the restaurants' automatic gratuity from 18% to 20% for the World Cup.

• "My servers are everything. They're like the quarterback to the rest of the team," she says.
• "Doing this makes the server see that I'm putting them first, ... and I care about them and their money."

The big picture: Tipping isn't customary in many countries, and the U.S. version of it is unusually central to worker pay.

• In America, tipped workers can be paid as little as $2.13 an hour as long as tips bring them up to the $7.25 federal minimum wage.
• Tipping originated in feudal Europe, where royalty tipped servants in addition to paying them a living wage. The U.S. later adopted the practice after enslavement ended, using it as a way to keep Black workers in poverty.
• "Restaurants wanted to be able to continue to access free Black labor," Saru Jayaraman, president of advocacy group One Fair Wage, tells Axios. "So they mutated tipping from being an extra bonus on top of the wages... to becoming a replacement for wages."

Case in point: Jessica Ordeñana, a NYC bartender, tells Axios her restaurant is adding automatic gratuity for tourists, but that occasionally gets missed during busy game days.

• She says a large group of foreign fans came in to watch Tuesday's match between Argentina and Algeria and ran up a bill of about $300.
• "They left like a $4 tip, and that was really, really disgusting. We depend on [tips], but unfortunately we cannot depend on them, because of how low they are," Ordeñana says.

Between the lines: David Cooper, director of the Economic Analysis and Research Network, tells Axios research shows the poverty rate for tipped workers is "dramatically lower" in states like California, Minnesota and Montana where servers receive tips on top of the full minimum wage versus those in states that follow the federal tipped minimum wage.

• Poverty rates for non-tipped workers are "essentially the same" across both groups of states, which suggests the tipped wage policy itself is a key driver, he says.

Zoom in: Unionized servers and bartenders at SoFi Stadium in Los Angeles authorized a strike a week before the tournament's opening match, threatening a walkout.

• The strike was averted after the union reached an agreement with management. Tipped workers at SoFi won a 30% pay increase.

The bottom line: Jayaraman says she hopes the World Cup "shines a light" on tipped workers' vulnerability — and the year-round insecurity a temporary service charge can't fix.

• "We always say your tips go up and down, month to month, shift to shift, season to season, but your bills don't go up and down, they just go up and up."

Go deeper: World Cup collides with Trump's America First agenda