They care now and when they came up with those 12 categories, Aeromexico and Copa will ask you to sign an affadavit if youre an American.
I'll bet that any airline flying to both the US and Cuba on a regular basis are utilizing the affadavit for Americans , Cubana has no US routes so they don't have worry about it.They won't fly into the US because they don't want their planes seized.

I seriously doubt one will be filling out any form when flying to Cuba through a third country. Never happened in the past, why now ?
Its been going on for a few years, Gres. ALL the Mexican Airlines have you fill out the OFAC paperwork, so does Copa.
If you want a laugh do a fake booking on Air Canada or Westjet and see what happens half way through the booking process when they ask you about being American.
Cheers,
Terry

Never heard of the Honda Canada thing... You have a link ?
Gres, read this pile of crap.
Even though both the lessor and the lessee were in Canada the US Department of State is extracting $100,000+ CAN in fines out of Honda.
Disgusting.
Cheers,
Terry
Well talk about an unexpected kick in the boils!
Who knows if they will start clamping down on US folks going through a third country.
You never know.