The older “608”[1] system in North America was much simpler but the current “708”[2] standard does support specifying colours and fonts, but in my experience in the industry nobody uses those functions at all and just uses the 708 function to embed the older 608 payload data within the newer 708 data structure.
In UK/Europe the older/simpler format would be OP-42/OP-47 Teletext[3] which can be used for captions instead of the full-screen data pages, or DVB Subtitles[4], which get into more uses around “subtitles” in terms of language translation, rather than only the “closed caption” use case where it matches the content language. DVB subtitles can be sent as pre-rendered bitmaps or as data for client-side rendering.
There are very strong lobbying groups that push for accessibility in terms of captions (as well as the “DV” described video audio track) but my impression is that their focus is on the quantity of content that’s covered, and the quality (spelling, time-alignment), and I guess they don’t care as much about text styling.
The requirements are quite high in Canada[1] and have been expanding in the US as well[2].
The company I work for makes products for broadcast customers, around asset management, linear playout automation, and the playout servers that insert the captions (from files or live data sources) so working out how that all happens is part of every big project.
In UK/Europe the older/simpler format would be OP-42/OP-47 Teletext[3] which can be used for captions instead of the full-screen data pages, or DVB Subtitles[4], which get into more uses around “subtitles” in terms of language translation, rather than only the “closed caption” use case where it matches the content language. DVB subtitles can be sent as pre-rendered bitmaps or as data for client-side rendering.
[1] https://en.wikipedia.org/wiki/EIA-608 [2] https://en.wikipedia.org/wiki/CTA-708 [3] https://en.wikipedia.org/wiki/Teletext [4] https://en.wikipedia.org/wiki/Subtitles