Only VM and the app providers know the commercial arrangements between them for the streaming services to be available.
But certainly in the case of linear broadcast channels, there are transmission costs that all platforms get paid for carrying a channel on their service. Then carriage costs that the platform pays the broadcaster to provide their content.
I'm sure, in a free world, VM would rather all of the streaming apps content were provided to them without the need for apps - and just use their own OnDemand platform. Providers such as Netflix, Amazon, Disney, Discovery etc etc want to have more direct control without the need to go through platforms such as Virgin.
A high-level view....
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