Just read the docs, it seems that when you put a file in the CDN they distribute it on all edge servers and you paid for that (which is normal). But it would be great if you can chose on which servers you want the files distributed to. For example I might need the servers just from the european region.

If you have couple of files in the CDN it will not make sense, because the cost to distribute the files around will be marginal, but if you have many GB of data, distributing them to all unneeded servers might be not cost efficient.