So I emailed FT with my question, and they only sent a canned response about how FT no longer pays to contribute images to the free collection, which of course I didn't ask about!

Why can't they just answer my question?
Because you're dealing with HAL 9000 remnants currently situated in Bombay!

Indeed the free section is no longer operating and should never have been started. Initially, images were donated to the free section for a period of 18 months and the contributor received a once-only payment of $0.50. Then after a short term, FT unilaterally extended the period to 5 years without enabling a contributor that agreed to 18 months to withdraw from the extended time. Never give a commercial organization free images.