Buying dogs is a "new" thing in India - most of my grandmother's dogs in the past have been street dogs. They've all been awesome in their own way.
In the modern context - Its all about networking, and marketing. In singapore, we have a handful of organisations - like ASD and SOSD, who run programs to help "Singapore Specials" on the street, help do trap/neuter/release programs for humane population control (so fewer stray puppies), and generally create a framework for the things you need to get people to adopt dogs.
You noticed I used the term "Singapore Special" - its not a street dog. Its a uniquely local canine - and quite often expatriates adopted them. In singapore, there's other reasons, but its a selling point for more bougious folks. "Look, even the foreigners are adopting local dogs".
And of course, the power of social networking to get folks and dogs together. I believe SOSD runs training classes. They get people to foster dogs, and find homes for them were possible. They tell stories and use ..
Well - you advertise. And you don't play fair. Look at that widdle face.
I think that facebook post speaks for itself. Its really a process - build awareness, build a brand, replace the prejudices people have with pride in our dogs, and people will be more likely to adopt.
You also make sure the animal's taken care of - and not turned out onto thr street(and there's no shame if it really dosen't work out and the dog's forever home is elsewhere) and that fostering, training and such is handled. In a sense - you need a certain degree of infrastructure in place.
By actually working to humanely reduce the population of strays - we're also solving a bigger problem.
Its also worth remembering many purebred and "designer" crossbreeds need rehoming too, as owners with the same mindset as yours get "tired" of their dogs. On the other hand, there's a dog run regular who tends to adopt senior breeds that are usually hard to adopt out. Every dog matters, but finding the right forever home isn't easy.