"Shortwave radio" occupies the HF band, which has very different behavior from the UHF band discussed in this article. Amateur and commercial broadcasters have been using HF for transatlantic communications singe long before high-frequency trading existed.

Maybe this would have been a better response to the grandparent comment than downvoting it, as I don't think it's reasonable to expect most HN commenters to know the difference between UHF and HF (or even that they're different things), and the article makes no mention of it.