Originally Posted by xliioper

It's not really surprising when you take some time to think about it. Delta's "First Class" on international flights is vastly different from what most would usually consider "International First" to be which typically has lie-flats seats and exceptional service. International FC on Delta is basically exactly the same as their domestic FC in terms of both product (they use the same planes as they do on domestic routes) and service. Pricing is also much cheaper than what you would find on a true "International First" product. Given that they don't provide lounge access for domestic FC, it naturally follows that they wouldn't provide it on these shorter-haul international FC flights where the product is exactly the same. European airlines like KLM and Air France call their short-haul Europe premium cabins "Euro Business" so as not to confuse it with true First Class products.

American's policy is somewhat of a hybrid between Delta's and United's. While they provide lounge access on FC flights to Central and South America, their policy does not provide for lounge access on FC flights to/from Canada, Mexico (except Mexico City), and the Caribbean (which DL has also long excluded from lounge access). DL now excludes all of these on their flights except for southern South America where they have D1 flights.