> Speed. It all comes down to speed.

GP isn't wrong though. Most cameras embed a medium quality full-resolution JPEG along a couple different thumbnails in raw files, so saving raw+normal JPG is kinda pointless, because the raw already contains that jpeg. Raw+jpg is only easier in the sense that many/most non-vendor tools - even viewers - can't properly handle the embedded jpg so it's easier to just duplicate the storage (e.g. 50 MB for the raw + 10-20 MB for the JPG) and take the hit on storage consumption/transfer time.

My Olympus camera only embeds 1MP thumbnails in RAWs, but my iPhone embeds full JPEGs.

It varies by vendor and sometimes even firmware revision.