@BryanGreyson
Before proposing new laws, one should consider the industry and the nature of compliance. Laws are not aspirational goals for society's moral advancement but shackles on individuals of the here-and-now. So one needs to consider the impact on the poor producer of media and the reactions and sham compliance of the wealthy.
1) Who does the subtitles? By default, YouTube has machine attempts at transliteration. Sometimes the result is useless and that's in the language the tool was expecting. Similarly, human subtitle creators have varying levels of success. Timing plays an issue and subtitles have given away plot points and jokes before the actors on the screen react.
2) Whose subtitles? Films are art. Films are messages. Whose message is the subtitles? If a time-traveling samurai appears in the Althing (Iceland's legislature, host to very few speakers of Japanese), do you translate their startled demands to know what is happening or caption it as [foriegn speech]? If the actor flubs a line do the subtitles reflect the script or what the actor actually said? In a documentary, if the interviewee says something unintelligible or unparsable, what would the captions read?
3) How much will this cost? Creating and distributing media today is cheap provided one is willing to partner with ads. But subtitles are a new cost; a new skill to develop and perhaps new staff to hire.
4) What's the cheapest way for unelightened companies to comply? Will that be better than no subtitles at all? Who determines if the subtitles are good enough? Should they be allowed to charge additional fees for additional subtitles? #enshittification