Question: There are a lot of variants of the CSV "standard" (or lack thereof). I've never personally see any that use an escape character (like `\`) instead of surrounding each field with double quotes. Instead of `foo,bar,"foo,bar"` it would be `foo,bar,foo\,bar`. 

This would be handy for situations where a file needs to manually inspected or edited by hand. When counting commas to find the right field, it seems that it would be easier to tell which ones were not field separators if they escaped instead of quoted. 

I don't see how it would make a difference from a parsing perspective, though.

Why quote instead of escape?

Answer: 
Your question includes the answer, when you wrote "I don't see how it would make a difference from a parsing perspective, though"

There is no compelling reason, it just is. Csv is a data format, so the main goal is to be parseable.
Chicken and egg.

If I was defining a spec, I'd escape for the reasons that you state. But any CSV parsing tool that you encounter (including Excel, sqloader, etc) is almost certain to use quoting, not escaping. So if you want to produce it, you need to produce it quoted. If you want to consume it, it is safe to assume that whoever generates it will quote.