With a small pension and Social Security, he said, he and his wife are “just getting by.”

“It’s devastating,” Mr. Adair said. “You go through the stages just like dying. First you can’t believe it. You’re so sure and your wife is so sure, and even the recruiter is. Then you get mad.” By the end, you feel like giving up, he said.

Wanted: Greener Employees

Hiring complaints and lawsuits are rarely filed because they are difficult to prove and the cost is high, said Robert E. Weisberg, a regional attorney with the federal Equal Employment Opportunity Commission in Florida.

To bring a case against Seasons 52, a national restaurant chain, Mr. Weisberg said, the commission looked to establish a pattern of bias over a period of years by combining statistical analyses with testimony from applicants.

The agency examined whether the chain could have hired so few applicants 40 or older if there had been no age discrimination, and calculated the odds at less than one in 10,000, according to court documents. The commission also collected affidavits from 139 applicants at 35 restaurants.

George Simmons was 45 when he applied at a Seasons 52 in Lone Tree, Colo., in 2014. “My interview was going well until the interviewer asked me my age,” he stated. After he answered, he said, he was shown the door. “I asked what was the problem,” he said, “and the interviewer responded that the restaurant was looking for younger people.”

Heidi Barsaloux was 44 when she applied for a bartender position at a Seasons 52 in Schaumburg, Ill., in 2010. “An interviewer told me that they were not looking for people with that much experience and wanted people who were more green,” she said.