Since its only enabled in android 15 (android 14 has it but it's a developer setting). Apps need to be made to support/target android 15 and the setting be enabled by the app developer. With how large apps are, best guess is enabling a setting that tweaks the app needs meetings to discuss it, managers to approve it and loads of people things. The company behind the app would get mad if a single dev enabled it is what I'm trying to say.
And for small apps, if they work they work. Its a brand new setting most users can't use yet, so why go through the effort of enabling it?
For samsung, with how long one ui 7 has taken, I have a feeling the app devs are busy on that
