It used to be* that this was a requirement for Television (in the US). It seems that has gone so unenforced that nobody cares and just jacks the ad volume up.
I wonder if there's a requirement for radio as well.
Important takeaway from the linked article: "No specific penalties are given"
So there is a regulatory framework and, as the article describes, compliant technical means should be in place for devices sold in the respective market.
The open question is, how will this be applied in practice as well as how will this extend to radio and why not, to online services such as streaming platforms?
I wonder if there's a requirement for radio as well.
* Probably still is.