Barry, I'm glad you seem to do much better at reading than Jerrold is 😉
Yes, it does make a difference whether you drop a file on an application icon or on an open document window (roughly the equivalent between open and import).
It, however, also helps to read a thread in chronological order, as you'll see below.
About the "some regional settings" thing: I believe it roughly translaters to this:
Opening the file either through file open by right-clicking or by dropping it onto the application icon (or by simply using the file > open menu from within the application), probably works fine if:
1. the csv uses comma's to separate values, and points as decimal separators
2. your regional settings are the equivalent of US/North American (that is: use a point as a decimal separator)
However, if your regional settings are anything other than North American, or they do not comply with the US system of using points for decimal separators, and the csv you're opening does not comply with that format, you are probably better off using Yvan Koenig's or my solution.
Now, accuse me of whatever you want for thinking that a drag-and-drop soltution that merely changes the destination of the drop is "better" than a solution that involves fiddling with system settings. I'm fine with whatever side that coin drops (but this is where the chronological reading comes in).
I do, however, take offense with the "some regions" remark - from where I'm sitting, "some regions" would include the just about entire continent of Europe and then some.
And to be completely exhaustive: editing the csv itslef (as has been suggested multiple times here) is ok, as long as you only have the occassional file to open. For anything else, you might want to use a more serious work-around 😉