There’s a long tail of servers/bartenders who are against this as well because they work at expensive establishments and make bank off tips. Like high double digits an hour.
If the push to convert tips into wages ever becomes serious, conservative media will do its best to platform and promote these servers who stand to lose income off it. We gotta think of a rhetoric/messaging strategy to counter that.
To be fair it’s not a mysterious “they”, it’s just an option available for channel owners to set alternative thumbnails and then check which does better. I don’t think YouTube does this by itself if the uploader doesn’t enable it