[manigandham]

Because the format is video ads. They’re not paying for audio only. In fact most of them are optimized for video first with audio secondary by having visuals that communicate the message. You see the same with Facebook video ads in the feed.

If you don’t deliver what the advertiser paid for then you can’t charge for the ad.

Changing the format for audio ads that would run in the limited scenario of background video involves way too much effort and tooling to make it worth it.