You can not trademark echo for different areas. And podcast is different.
This way of reasoning makes me speachless.
P.s. goodreads might be a case though.
Amazon has very generic trademarks on the word echo. Podcasts are a recorded format meant for playback that provides commentary on different categories. Amazon definitely holds trademarks on these types of areas. That said, I'm not a lawyer so I can't speak to how much issue the overlap would cause but regardless Amazon has billions of dollars and could walk all over anyone they want so I'm pretty sure if this got bigger and they took issue with the use of the name Echo they could cause a lot of hell.
In fact amazon can't have (generic 'echo' word trademark) and does not have it in any sane part of world. All sane states do not allow generic trademark on common word.
My speechless was (and still is) about how much brainwashed must we be to consider it fine, normal and to actually defend such practice. Yuck.
By the way, Apple Computer (now just Apple) was sued by Apple Corps and had to pay $80k, and that was in England, not in the US.
Aside from joining the app because you love podcasts, it may interest you because it has some cool tech behind it. ie) Echo is not a podcast player, but we connect to your podcast player. We give every user their own unique podcast feed, generated with a list of every episode that they want to listen to. This feed can be added to your podcast player just like any other podcast feed. When a user finds an episode on Echo, they just have to tap a button and it will be ready in their podcast player from them to listen to it. Try it out, it's pretty slick in my opinion.
Similar solutions have been built, for instance, Patreon generates custom feeds for podcasts which include episodes available only to paid users. However, this is the first time users have the ability to generate a custom podcast feed, for themselves.