Usage of 'at' and 'in' for cities
Solution 1:
Yes and no. I'd agree that the preposition in would normally be the better word to use, particularly when an activity happens inside the city limits. However, that's not hard-and-fast, and I don't quite like the inflexibility of the rule as you stated it: 'in' has to be used for cities.
For example, the word at can sometimes be used to mean "near", as in,
The soldiers clashed at Gettysburg.
The word at might also be used when talking about a momentous event, where the city is considered a meeting place:
The treaty was signed at Versailles.
In the case of:
Printed at Chennai, Bangalore, Hyderabad
I read that as:
Printed at [the presses in] Chennai, Bangalore, and Hyderabad
which sounds just fine to me.
When the use of a preposition doesn't match a rule of thumb you've been taught, chances are that the word is simply being used in a way that's not quite so ordinary – not that the "wrong word" has been used.
Ah, prepositions! Those two- and three-letter words can often be much more flexible than we sometimes initially realize.
Solution 2:
You are partly correct that the usage should be in for a city or country and at for an exact address when describing a location.
But even with exact addresses, in should be used for first person:
- I am in London
- I am on Brompton Road
- I am in Harrods
Another related usage is on for a street — if you are not giving a specific location then this should be used:
- Harrods Store is at 87–135 Brompton Road
- Harrods is on Brompton Road
- Harrods is in London
There can however be some confusion when a district name is also a street name. For example, a store may be in the Oxford Street area of London without being on Oxford Street itself. This is conversationally extended to say that a place is off somewhere (e.g. 'off Oxford Street') — meaning 'not actually on, but not far from'.
Solution 3:
I've seen "at" used in older writings. For example, I've seen in old newspapers, "Mr. Smith is superintendent of the public schools at Springfield" or "Mr. Smith owns the large factory at Springfield." I think it's just an evolution of language thing.
Solution 4:
You use "in" for a city because you can be in the city or will be in(side) the city. Same for a country. You will be inside the country.
For places like a store both in and at can be used.
I will meet you at the cafe. A little ambiguous.
I will meet you in the cafe. You should expect to meet the person inside the cafe.
For streets and addresses, you cannot be inside these things. So you would use at or on.
Solution 5:
If at is used for cities, it is usually because of an implied location within the cities.
For example,
The plane stops at Dallas on the way to San Francisco (implies DFW Airport).
Next weekend, Chicago will play against Dallas at Atlanta (implying Georgia Dome stadium).
In the case of the paper given above, they probably mean specific printing presses in these cities (but surely, this is not so obvious as in the above two examples).