Amazon is also charging less than half of what Netflix does, for 4k, and is still the cheapest of all the streaming services. I naively assume they're feeling the pressure more than Netflix does.
Although there’s a few great series and movies in the catalog, even at half the price it’s not great value. I’d be very surprised if more than 5% of its subscribers only subscribe to Amazon Video, vs. getting it as a freebie with Amazon Prime.