Gokuldham has got mixed crowd of middle class and upper middle class people but except sodhi no one has got a four wheeler. They may not be very rich but atleast financially stable enough to afford a car, even on loans. Fine that bhide may not be in the condition of buying and maintaining a car but others certainly can.
Jetha- He runs his own business and have people working for him. He is financially sound too. Long back he was seen sharing information of his financial status to a goon in jail, who later turns up to jetha's home and ask for hafta. Gada family is financially sound and can afford luxuries(many if not all) and even got two flats within gokuldham only but still jetha couldn't buy a car for himself. Why?
Mehta- Mehta is a successful writer, who, I think works for a publishing company(not sure as they have never shown about his job profile apart from being a writer). He, many times has been seen working from his own cabin at work sitting at a large mahogany desk. Taarak and anjali don't have kids too so no responsibility of a child's education and his future.
Aiyer- Aiyer is a successful scientist and has also got a promotion recently. He must be getting paid to atleast afford a car. Like Taarak and anjali aiyers too don't have kids to raise, so they too are free from a big responsibilites. So do they spend all the money on babita's clothes, makeup and accessories becuse aiyer is always seen in plain pastel colour shirts with plain trousers.
Dr. Hathi- Hathis are big time foodies. Apart from gorgin on loads and loads of food, every now and then they order food from restaurants, which means they are living a pretty comfortable life. They haven't been seen cribbing over money like bhide.
Apart from not showing any development in the story, the cvs has not given any attention to any development in the characters and their financial condition. So this is the least we can except from cvs and makers of the show.