well you also need to add the cost of a Apex unit too.
So you need 3 things to equal what Maven does by itself.
You are correct - there is a controller cost associated with the Trident. However Neptune never promoted the Trident as a stand alone kit. Point being most who buy it are already in the ecosystem. I do agree that someone new or deciding to enter has to look at that as a factor.
Hydros on the other hand released a new product several years after. I am not knocking that as that wouldn't be cool. Short answer would be they had a clean slate to work with.
I'm sure both will do well respectively.