Hypothesis: people aren't familiar with New York's trains. It's a world-class network the likes of which we don't otherwise have in North America. (Sorry Toronto.) So when they see eVTOLs, they emotionally map it to their local trainless context.
In Ireland, everyone thinks it's pretty ridiculous that there's no train to Dublin Airport (all going well, it will finally have one in 2036 or so, after _many_ false starts). Dublin's a city of about 1.5 million people. It's pretty incomprehensible that a city ten times the size wouldn't have one.
EDIT: Oh, wait, misread, I thought you meant a direct train from Grand Central to the airport.
It’s a single, low-bullshit transfer. Frankfurt Airport also requires a connection for terminals 2 and 3 [1].
[1] https://www.frankfurt-airport.com/en/transport-and-parking/t...