Why do relays need zap-splits? 
Their offer is actually scarce (unlike content, software, etc...).
They can set prices.

If you provide commodity relays and you'll get commodity prices, of course.
Cater to niches and you''l get niche prices.  

 I agree zap splits are more adjunct. We’re working on the subscription model. 🫡 

 Just thinking zap splits could be a cool way to support free relays as a tip for their altruism…