I get that FCPX can't import .mts files directly, that it needs the metadata on the rest of the card.
No, scratch that, I sort-of get why it needs all the surrounding crap, even though ClipWrap can just copy the file into a new wrapper, call it a mov, and make FCPX happy. That makes some kind of WEIRD TWISTED NO-IT-DOESN'T sense.
I get that FCPX can copy your card into a neat little wrapper which it stores in a 'Final Cut Archives' folder. Fine. Whatever.
What I just don't get at all is why it utterly fails to do anything with a straight Finder copy of the entire contents of a card. It has to be a Final Cut Pro X Camera Archive. So if you have the complete folder structure … tough. No-go.
Only: You can cheat! Fire up Disk Utility, make yourself a new disk image of whatever size your card was, mount it, copy the AVCHD folder into it... and FCPX will import from that.
What? How does this make any sense?