I find FireTV stick (from Amazon) to be applying in this respect, it doesn't appear to know command that direct them input to a specific app. When I have Google open and ask it to search for $search-string it will do it in the Amazon store context, ie offer to sell me a program rather than find the string on Google.

Annoying. It relates to the lack of discoverability in voice interfaces, there may be an incantation to get the behaviouyr I want but there's no way within the interface that such methods is revealed.