One cabby recently sold his taxi because there was not enough work. He is leasing one now but may quit altogether, he said. “Most weeks you’re just trying to cover your costs.”

Before Uber, Mr. Walsh would have 20 fares a day. Now the number is closer to five. “They want to price us out of the market,” he said, “and then they’ll raise prices — you watch.”

And when cars go driverless, he added bitterly, “cabbies and Uber drivers will both be history.”

Mrs. Bakkali shrugs at the idea. She grew up without running water or a phone. To visit her grandparents, she had to walk — for a day.

“So much has changed in my life,” she said. If someday driving is no longer an option, she may start her own business, she said. Embroidery, perhaps, or sewing.

Mr. Walsh accepts that black cabs have been slow to adapt to change. Credit-card machines were made mandatory only last fall. Ride-hailing apps for black cabs remain fragmented. But he believes that his brain can beat a navigation system any day. Years ago, he took part in a research project at University College London that found that memorizing a map of the city resulted in an enlarged hippocampus.

“Cabdrivers’ brains are bigger,” Mr. Walsh said proudly.

Navigation systems do not know nicknames like the Policeman’s Hook. They cannot deal with incomplete addresses and do not know the best shortcuts when traffic is bad. And they cannot tell you where to buy the best salt beef bagels.

“We’re still better than the machines,” he said. “But who will come and protect us?”