I'm curious too. As a complete outsider to that problem space, it seems like a lot of the tech was designed/created in an era before wide-spread broadband and internet-based content distribution. I'm sure a lot of it is simply that new hardware from that vendor is largely a drop-in replacement for each station, so there's no need to re-engineer their broadcast booth.
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I guess HN is the new Reddit. Downvotes, not a single response. You can do better, HN.