Comment by danaris

That's also ahistorical.

The green bubbles came first.

iMessage didn't even exist for the first few years of the iPhone's life. All messages were green. Green could not have been chosen to indicate it cost money, because there was nothing to distinguish it from.

Then, in 2011 (IIRC), iMessage was introduced, and the blue bubbles were to indicate both that it doesn't cost money, and that it supports several other capabilities (which have changed over the years—IIRC, it did not start out with end-to-end encryption, so the people boldly asserting that that's the primary reason for the distinction are also wrong).