I'm going to focus on car repair. At first, I thought of helping spanish speakers learn english, but only 8% of people have low proficency of english. And the demand would be lower because my governments already provide free translation services.
But the automotive repair demand is different, I feel. I think almost every household has a vehicle. And vehicle repair is necessary for maintaining a car. even the governments have laws and requirements for drivers, which also affect the demand for vehicle repair.