Answer by Nikunj Bhatia:
A dot matrix printer is still used today because it serves a very specific purpose and does so very, very cheap for the thing it does.
1. Multiple pages printing:
There are no printers that are cheap and can print on multiple papers at the same time. The dot matrix printer can be used to print one original and 3 carbon copies of the same document at the same time. This makes printing and keeping track of duplicates, triplicates and quadruplicates very easy.
For example, the reservation chart that is stuck outside the train, has multiple copies. One copy goes to the head office, one to the ticket checker, one on the platform and one the train. The multiple copies are printed simultaneously and it is because of the dot matrix printer.
The Indian management system and businesses rely heavily on duplicates and triplicates. Trust me when I say that.
2. Versatile printing:
There is no limitation on the paper dimension you can print on with the dot matrix printer. According to my estimates, Mumbai local train ticket is small enough that you can print upto six on a A4 page and the inter state tickets are such that one A4 can accommodate 3 tickets. One dot matrix printer can print the Local train ticket, the Inter state ticket, the official documents, and any other document you can think of.
It can't print images but why do you need to print images in an office?
It can print graphs and tables perfectly fine.
3. Backwards compatibility:
Indian railways system dates back to God knows when. They still have a MS-DOS style software they use to print out tickets. I doubt there is any other printer that can not only deal with that old software; but also be sure that it will work with the latest windows platform too, if they ever decide to upgrade.
4. Robust and heavy duty:
The office printer has been there for 9 years. It had a full servicing done once when a lot of paper was getting jammed in it and it took 80 rupees. It was a one off problem because the clerk had pulled the paper out forcibly. That is the only problem it has had. It can print all day every day.
5. Ease of use:
These dot matrix printers are extremely easy to understand. You can easily open one up and reassemble it if you have an issue. When you think about it, most of the people working with these printers are not engineers. It has just two or three troubleshooting procedures that anyone can perform. There is no issue that cant be fixed.
We have one dot matrix printer in our office and it prints out roughly 1000 A4 size pages before running out of ink. It takes 20 rupees and 5 minutes to refill.
We have one black and white laser printer . It can not print multiple pages. It jams if the paper is slightly folded. It chokes if we put in a smaller sheet. You can't troubleshoot it. The drivers on windows 7 are highly unreliable.
It costs 300 rupees to refill. It cant do any of the above tasks.
A dot matrix printer can replace any other printer (for office uses); no other printer can replace the dot matrix printer.
Edit: 1.5k upvotes in 3 days! Thanks a ton guys! Did not expect this kind of response!
Edit 2: I am humbled. Thank you!
Source: My experience.