It's sometimes done to game battery benchmarks, thus benefiting the manufacturer. Not sure how much of a thing it is these days, but there was a time when many Android OEMs shipped the phones in a basically broken state in a bid to do well in battery benchmarks; in particular, push notifications often wouldn't work reliably or at all in default configuration.

But yeah, I don't think the DMA's particularly relevant here.

I have experience with GPS related APIs in iOS. It’s a fucking nightmare to calibrate sensitivity and background activity. They keep changing parameters without warning or documentation. They aggressively suspend applications and services, even those categorised as navigation apps, unless a very particular set of criteria are met. Achieving background navigation was basically black magic. Every time we got it working, something would break.

Apple exempts themselves from all of these requirements for their own applications. They have access to the full specs, and have lots of advanced warning when change is on the road map.