Immigrant seeks right to sue Alabama over English-only driver's test

CNN reports:

The U.S. Supreme Court hears arguments Tuesday in a lawsuit filed by a Mexican immigrant who alleges Alabama violated the 1964 Civil Rights Act by giving driver's license tests in only one language: English.


Martha Sandoval, who came to the United States in 1987 and is a permanent resident, contends that English-language tests discriminate against her based on her "national origin," though the Civil Rights Act expressly forbids such discrimination by state agencies receiving federal funds.

Let's understand a little logic.To get a driver's license one should know English because that's the language on the road signs.So how is it safe for an insurance company to insure someone driving who doesn't speak or read English? How?